diff --git a/API.md b/API.md
index 1db188e..cb550f6 100644
--- a/API.md
+++ b/API.md
@@ -71,6 +71,9 @@
 ### Actividades (`/api/activities`)
 - `GET /api/projects/:projectId/activities` · `POST /api/projects/:projectId/activities`
 - `GET /api/activities/:id` · `PUT /api/activities/:id`
+- `DELETE /api/activities/:id` — bloqueado con `400` si la actividad tiene tareas (hay que
+  eliminarlas primero); limpia comentarios/adjuntos de la actividad de paso (no hay FK física
+  cruzada). Arrastra `activity_dependencies` por `ON DELETE CASCADE`.
 - `POST /api/activities/:id/dependencies` · `DELETE /api/activities/:id/dependencies/:dependsOnId`
 
 ### Tareas (`/api/activities/:activityId/tasks`)
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 0cc7fc5..d574e81 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,16 @@
 # Changelog - project.linkedcorp.net
 
+## [1.13.0] - 2026-09-15
+### Added
+- Eliminar actividad: `DELETE /api/activities/:id` (no existía) + botón "Eliminar" en el listado
+  de actividades, con popup de confirmación. Si la actividad tiene tareas, se bloquea con un
+  mensaje claro ("Esta actividad tiene N tarea(s). Elimina primero las tareas antes de borrar la
+  actividad.") en vez de borrar en cascada silenciosamente.
+### Changed
+- Adjuntos: la lógica de borrar archivo + fila (antes solo inline en el controller) se movió a un
+  nuevo `attachments/service.js` reutilizable, usado tanto por el borrado individual como por el
+  borrado en cascada al eliminar una actividad (evita archivos huérfanos en disco).
+
 ## [1.12.5] - 2026-09-14
 ### Changed
 - Listado de Proyectos: columna "Creado" reemplazada por "Actualizado" (fecha y hora), y es ahora
diff --git a/VERSION b/VERSION
index e0a6b34..feaae22 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-1.12.5
+1.13.0
diff --git a/backend/package.json b/backend/package.json
index 753d8d2..eb35df3 100644
--- a/backend/package.json
+++ b/backend/package.json
@@ -1,6 +1,6 @@
 {
   "name": "project-linkedcorp-backend",
-  "version": "1.12.5",
+  "version": "1.13.0",
   "private": true,
   "type": "module",
   "main": "src/server.js",
diff --git a/backend/src/modules/activities/controller.js b/backend/src/modules/activities/controller.js
index 6296415..6e73305 100644
--- a/backend/src/modules/activities/controller.js
+++ b/backend/src/modules/activities/controller.js
@@ -17,6 +17,11 @@ export const putActivity = asyncHandler(async (req, res) => {
   ok(res, await service.updateActivity(Number(req.params.id), req.body, req.currentUser));
 });
 
+export const deleteActivity = asyncHandler(async (req, res) => {
+  await service.removeActivity(Number(req.params.id), req.currentUser);
+  ok(res, { deleted: true });
+});
+
 export const postDependency = asyncHandler(async (req, res) => {
   const deps = await service.addDependency(Number(req.params.id), Number(req.body.dependsOnActivityId), req.currentUser);
   ok(res, deps, 201);
diff --git a/backend/src/modules/activities/repository.js b/backend/src/modules/activities/repository.js
index 0d9c25c..b1bb267 100644
--- a/backend/src/modules/activities/repository.js
+++ b/backend/src/modules/activities/repository.js
@@ -59,6 +59,11 @@ export async function updateProgress(id, progressPct) {
   await pool.query('UPDATE activities SET progress_pct = ? WHERE id = ?', [progressPct, id]);
 }
 
+// Arrastra activity_dependencies (ambos lados) y tasks por ON DELETE CASCADE.
+export async function remove(id) {
+  await pool.query('DELETE FROM activities WHERE id = ?', [id]);
+}
+
 export async function countTasks(id) {
   const [rows] = await pool.query('SELECT COUNT(*) AS c FROM tasks WHERE activity_id = ?', [id]);
   return rows[0].c;
diff --git a/backend/src/modules/activities/routes.js b/backend/src/modules/activities/routes.js
index 05852d7..99e4262 100644
--- a/backend/src/modules/activities/routes.js
+++ b/backend/src/modules/activities/routes.js
@@ -1,12 +1,13 @@
 import { Router } from 'express';
 import { requireAuth } from '../../middleware/auth.js';
-import { getActivity, putActivity, postDependency, deleteDependency } from './controller.js';
+import { getActivity, putActivity, deleteActivity, postDependency, deleteDependency } from './controller.js';
 
 const router = Router();
 
 router.use(requireAuth);
 router.get('/:id', getActivity);
 router.put('/:id', putActivity);
+router.delete('/:id', deleteActivity);
 router.post('/:id/dependencies', postDependency);
 router.delete('/:id/dependencies/:dependsOnId', deleteDependency);
 
diff --git a/backend/src/modules/activities/service.js b/backend/src/modules/activities/service.js
index 9ab205e..3ddb3e3 100644
--- a/backend/src/modules/activities/service.js
+++ b/backend/src/modules/activities/service.js
@@ -1,5 +1,7 @@
 import * as repo from './repository.js';
 import * as projectsRepo from '../projects/repository.js';
+import * as commentsRepo from '../comments/repository.js';
+import * as attachmentsService from '../attachments/service.js';
 import { recalcProjectProgress, canWriteProject } from '../projects/service.js';
 import { HttpError } from '../../utils/http.js';
 import { logAudit } from '../../utils/audit.js';
@@ -95,6 +97,27 @@ export async function updateActivity(id, payload, currentUser) {
   return repo.findById(id);
 }
 
+// Bloquea el borrado si hay tareas pendientes (a proposito: evita perder de vista trabajo real
+// hecho/por hacer solo porque alguien borro la actividad de un clic). El usuario debe vaciar el
+// checklist primero. Comentarios/adjuntos si se limpian solos, no llevan informacion de progreso.
+export async function removeActivity(id, currentUser) {
+  const activity = await repo.findById(id);
+  if (!activity) throw new HttpError(404, 'Actividad no encontrada');
+  const project = await getProjectOr404(activity.project_id);
+  if (!(await canWriteActivity(currentUser, project, activity))) {
+    throw new HttpError(403, 'No tienes permisos sobre esta actividad');
+  }
+  const taskCount = await repo.countTasks(id);
+  if (taskCount > 0) {
+    throw new HttpError(400, `Esta actividad tiene ${taskCount} tarea(s). Elimina primero las tareas antes de borrar la actividad.`);
+  }
+  await commentsRepo.removeByEntity('activity', id);
+  await attachmentsService.removeAllForEntity('activity', id);
+  await repo.remove(id);
+  await logAudit({ userId: currentUser.id, action: 'delete', entityType: 'activity', entityId: id });
+  await recalcProjectProgress(activity.project_id);
+}
+
 export async function addDependency(activityId, dependsOnActivityId, currentUser) {
   if (activityId === dependsOnActivityId) throw new HttpError(400, 'Una actividad no puede depender de si misma');
   const activity = await repo.findById(activityId);
diff --git a/backend/src/modules/attachments/controller.js b/backend/src/modules/attachments/controller.js
index d2581f9..3692d7f 100644
--- a/backend/src/modules/attachments/controller.js
+++ b/backend/src/modules/attachments/controller.js
@@ -5,6 +5,7 @@ import { logAudit } from '../../utils/audit.js';
 import { ROLES } from '../../middleware/auth.js';
 import { uploadsDir } from '../../middleware/upload.js';
 import * as repo from './repository.js';
+import { removeAttachment } from './service.js';
 
 const VALID_ENTITY_TYPES = new Set(['project', 'activity']);
 
@@ -43,9 +44,7 @@ export const deleteAttachment = asyncHandler(async (req, res) => {
   const canDelete = [ROLES.SUPERADMIN, ROLES.ADMIN, ROLES.IT_MANAGER].includes(req.currentUser.roleCode) || attachment.uploaded_by === req.currentUser.id;
   if (!canDelete) throw new HttpError(403, 'No puedes eliminar este adjunto');
 
-  await repo.remove(attachment.id);
-  const filePath = path.join(uploadsDir, attachment.filename);
-  fs.promises.unlink(filePath).catch(() => {});
+  await removeAttachment(attachment);
   await logAudit({ userId: req.currentUser.id, action: 'delete', entityType: attachment.entity_type, entityId: attachment.entity_id, detail: { attachmentId: attachment.id } });
   ok(res, { deleted: true });
 });
diff --git a/backend/src/modules/attachments/service.js b/backend/src/modules/attachments/service.js
new file mode 100644
index 0000000..a97a2a1
--- /dev/null
+++ b/backend/src/modules/attachments/service.js
@@ -0,0 +1,22 @@
+import path from 'node:path';
+import fs from 'node:fs';
+import { uploadsDir } from '../../middleware/upload.js';
+import * as repo from './repository.js';
+
+async function unlinkQuiet(filename) {
+  await fs.promises.unlink(path.join(uploadsDir, filename)).catch(() => {});
+}
+
+// Borra la fila y el archivo en disco. Unico lugar que hace esto — reutilizado tanto por el borrado
+// individual (controller) como por el borrado en cascada al eliminar la entidad duena.
+export async function removeAttachment(attachment) {
+  await repo.remove(attachment.id);
+  await unlinkQuiet(attachment.filename);
+}
+
+// Usado al borrar la entidad duena (actividad, proyecto): limpia sus adjuntos (fila + archivo) de
+// paso, ya que no hay FK fisica cruzada (entity_type/entity_id es polimorfico) que lo haga por cascada.
+export async function removeAllForEntity(entityType, entityId) {
+  const files = await repo.findByEntity(entityType, entityId);
+  for (const file of files) await removeAttachment(file);
+}
diff --git a/backend/src/modules/comments/repository.js b/backend/src/modules/comments/repository.js
index 8db1a22..e6b6f68 100644
--- a/backend/src/modules/comments/repository.js
+++ b/backend/src/modules/comments/repository.js
@@ -10,6 +10,12 @@ export async function findByEntity(entityType, entityId) {
   return rows;
 }
 
+// Usado al borrar la entidad duena (actividad, proyecto): limpia sus comentarios de paso, ya que
+// no hay FK fisica cruzada (entity_type/entity_id es polimorfico) que lo haga por cascada.
+export async function removeByEntity(entityType, entityId) {
+  await pool.query('DELETE FROM comments WHERE entity_type = ? AND entity_id = ?', [entityType, entityId]);
+}
+
 export async function create({ entityType, entityId, userId, message }) {
   const [result] = await pool.query(
     'INSERT INTO comments (entity_type, entity_id, user_id, message) VALUES (?, ?, ?, ?)',
diff --git a/frontend/package.json b/frontend/package.json
index ef34f52..8182d80 100644
--- a/frontend/package.json
+++ b/frontend/package.json
@@ -1,7 +1,7 @@
 {
   "name": "project-linkedcorp-frontend",
   "private": true,
-  "version": "1.12.5",
+  "version": "1.13.0",
   "type": "module",
   "scripts": {
     "dev": "vite",
diff --git a/frontend/src/pages/Proyectos/ProjectActivitiesTab.jsx b/frontend/src/pages/Proyectos/ProjectActivitiesTab.jsx
index 09ab4f4..23a74cf 100644
--- a/frontend/src/pages/Proyectos/ProjectActivitiesTab.jsx
+++ b/frontend/src/pages/Proyectos/ProjectActivitiesTab.jsx
@@ -1,8 +1,9 @@
 import { useState } from 'react';
-import { Plus, Save } from 'lucide-react';
+import { Plus, Save, Trash2 } from 'lucide-react';
 import { useUi } from '../../context/ui-context.jsx';
+import { useAuth } from '../../context/auth-context.jsx';
 import { useAsync, useAction } from '../../hooks/useAsync.js';
-import { listActivitiesByProject, createActivity, getActivity } from '../../services/activities.js';
+import { listActivitiesByProject, createActivity, getActivity, deleteActivity } from '../../services/activities.js';
 import { listCatalog } from '../../services/catalogs.js';
 import { listUsers } from '../../services/users.js';
 import { ListView } from '../../components/ListView.jsx';
@@ -18,7 +19,8 @@ import ActivityDetailPanel from './ActivityDetailPanel.jsx';
 const EMPTY_FORM = { name: '', description: '', responsibleUserId: '', priorityId: '', statusId: '', startDate: '', dueDate: '', isMilestone: false };
 
 export default function ProjectActivitiesTab({ projectId }) {
-  const { t, pushToast } = useUi();
+  const { t, pushToast, openDialog } = useUi();
+  const { user: currentUser } = useAuth();
   const runAction = useAction();
   const { data: activities, reload } = useAsync(() => listActivitiesByProject(projectId), [projectId]);
   const { data: priorities } = useAsync(() => listCatalog('priorities'), []);
@@ -55,6 +57,25 @@ export default function ProjectActivitiesTab({ projectId }) {
     if (selected) setSelected(await getActivity(selected.id));
   }
 
+  function confirmDelete(row) {
+    openDialog({
+      tone: 'warning',
+      title: t('common_confirm_delete_title'),
+      message: t('common_confirm_delete_msg'),
+      actions: [
+        { label: t('common_cancel'), variant: 'standard' },
+        {
+          label: t('common_delete'), variant: 'danger',
+          onClick: () => runAction(async () => {
+            await deleteActivity(row.id);
+            await reload();
+            pushToast({ tone: 'success', message: t('common_saved') });
+          }),
+        },
+      ],
+    });
+  }
+
   const columns = [
     { key: 'code', label: t('activity_code') },
     { key: 'name', label: t('common_name') },
@@ -86,6 +107,9 @@ export default function ProjectActivitiesTab({ projectId }) {
         getSearchHaystack={(a) => `${a.code} ${a.name} ${a.responsible_name || ''}`}
         getRowKey={(a) => a.id}
         onRowClick={openActivity}
+        rowActions={currentUser?.roleCode !== 'viewer' ? (a) => [
+          { label: t('common_delete'), icon: Trash2, danger: true, onClick: () => confirmDelete(a) },
+        ] : undefined}
       />
 
       <DetailPopup open={creating} title={t('activity_new')} onClose={() => setCreating(false)} width={640} height={560}>
diff --git a/frontend/src/services/activities.js b/frontend/src/services/activities.js
index d237125..f658116 100644
--- a/frontend/src/services/activities.js
+++ b/frontend/src/services/activities.js
@@ -4,5 +4,6 @@ export const listActivitiesByProject = (projectId) => api.get(`/projects/${proje
 export const createActivity = (projectId, data) => api.post(`/projects/${projectId}/activities`, data);
 export const getActivity = (id) => api.get(`/activities/${id}`);
 export const updateActivity = (id, data) => api.put(`/activities/${id}`, data);
+export const deleteActivity = (id) => api.delete(`/activities/${id}`);
 export const addDependency = (id, dependsOnActivityId) => api.post(`/activities/${id}/dependencies`, { dependsOnActivityId });
 export const removeDependency = (id, dependsOnId) => api.delete(`/activities/${id}/dependencies/${dependsOnId}`);