diff --git a/frontend-web/src/components/workspace/agents/agent-card.tsx b/frontend-web/src/components/workspace/agents/agent-card.tsx
index cc136d61..86f32274 100644
--- a/frontend-web/src/components/workspace/agents/agent-card.tsx
+++ b/frontend-web/src/components/workspace/agents/agent-card.tsx
@@ -66,10 +66,11 @@ export function AgentCard({ agent }: AgentCardProps) {
   const isOwned =
     !isBuiltin && agent.user_id !== null && agent.user_id === currentUserId;
   const isFromOthers = !isBuiltin && !isOwned;
-  // System admins are allowed to edit built-in agents in place. Delete and
-  // publish-toggle stay owner-only — built-ins shouldn't be removable, and
-  // they are inherently visible to everyone so toggling published is moot.
+  // System admins are allowed to edit and delete built-in agents.
+  // Publish-toggle stays owner-only — built-ins are inherently visible to
+  // everyone so toggling published is moot.
   const canEdit = isOwned || (isBuiltin && isAdmin);
+  const canDelete = isOwned || (isBuiltin && isAdmin);
 
   useEffect(() => {
     if (!editOpen) {
@@ -241,7 +242,7 @@ export function AgentCard({ agent }: AgentCardProps) {
             <MessageSquareIcon className="mr-1.5 h-3.5 w-3.5" />
             {t.agents.chat}
           </Button>
-          {(canEdit || isOwned) && (
+          {(canEdit || canDelete || isOwned) && (
             <div className="flex gap-1">
               {isOwned && (
                 <Button
@@ -270,7 +271,7 @@ export function AgentCard({ agent }: AgentCardProps) {
                   <SquarePenIcon className="h-3.5 w-3.5" />
                 </Button>
               )}
-              {isOwned && (
+              {canDelete && (
                 <Button
                   size="icon"
                   variant="ghost"
diff --git a/offline-backend-20260512/backend/app/gateway/routers/agents.py b/offline-backend-20260512/backend/app/gateway/routers/agents.py
index 11527961..4508bc0f 100644
--- a/offline-backend-20260512/backend/app/gateway/routers/agents.py
+++ b/offline-backend-20260512/backend/app/gateway/routers/agents.py
@@ -470,8 +470,15 @@ async def delete_agent(agent_id: str, request: Request) -> None:
     try:
         store = get_agent_store(request)
         user_id = _current_user_id(request)
-        await _get_owned_or_raise(store, agent_id, user_id)
-        deleted = await store.delete(agent_id, user_id)
+        is_admin = _is_admin_user(request)
+        _, edit_mode = await _get_editable_or_raise(
+            store, agent_id, user_id, is_admin=is_admin
+        )
+
+        if edit_mode == "admin":
+            deleted = await store.delete_builtin(agent_id)
+        else:
+            deleted = await store.delete(agent_id, user_id)
         if not deleted:
             raise HTTPException(status_code=404, detail=f"Agent '{agent_id}' not found")
 
diff --git a/offline-backend-20260512/backend/packages/harness/deerflow/persistence/agents/base.py b/offline-backend-20260512/backend/packages/harness/deerflow/persistence/agents/base.py
index dce4a983..225f8d13 100644
--- a/offline-backend-20260512/backend/packages/harness/deerflow/persistence/agents/base.py
+++ b/offline-backend-20260512/backend/packages/harness/deerflow/persistence/agents/base.py
@@ -47,3 +47,12 @@ class AgentStore(ABC):
     @abstractmethod
     async def delete(self, agent_id: str, user_id: str) -> bool:
         raise NotImplementedError
+
+    @abstractmethod
+    async def delete_builtin(self, agent_id: str) -> bool:
+        """Delete a built-in agent (user_id IS NULL).
+
+        Caller is responsible for authorization — this method does NOT check
+        any user identity and returns ``False`` if the target is not a built-in.
+        """
+        raise NotImplementedError
diff --git a/offline-backend-20260512/backend/packages/harness/deerflow/persistence/agents/memory.py b/offline-backend-20260512/backend/packages/harness/deerflow/persistence/agents/memory.py
index 3220b330..6a98d15d 100644
--- a/offline-backend-20260512/backend/packages/harness/deerflow/persistence/agents/memory.py
+++ b/offline-backend-20260512/backend/packages/harness/deerflow/persistence/agents/memory.py
@@ -107,3 +107,10 @@ class MemoryAgentStore(AgentStore):
             return False
         self._agents.pop(agent_id, None)
         return True
+
+    async def delete_builtin(self, agent_id: str) -> bool:
+        row = self._agents.get(agent_id)
+        if row is None or row.get("user_id") is not None:
+            return False
+        self._agents.pop(agent_id, None)
+        return True
diff --git a/offline-backend-20260512/backend/packages/harness/deerflow/persistence/agents/sql.py b/offline-backend-20260512/backend/packages/harness/deerflow/persistence/agents/sql.py
index 97b33ece..87ed7502 100644
--- a/offline-backend-20260512/backend/packages/harness/deerflow/persistence/agents/sql.py
+++ b/offline-backend-20260512/backend/packages/harness/deerflow/persistence/agents/sql.py
@@ -128,3 +128,12 @@ class AgentRepository(AgentStore):
             await session.delete(row)
             await session.commit()
             return True
+
+    async def delete_builtin(self, agent_id: str) -> bool:
+        async with self._sf() as session:
+            row = await session.get(AgentRow, agent_id)
+            if row is None or row.user_id is not None:
+                return False
+            await session.delete(row)
+            await session.commit()
+            return True
diff --git a/offline-backend-20260512/backend/tests/test_agents_backend.py b/offline-backend-20260512/backend/tests/test_agents_backend.py
index 070be227..f53b2caf 100644
--- a/offline-backend-20260512/backend/tests/test_agents_backend.py
+++ b/offline-backend-20260512/backend/tests/test_agents_backend.py
@@ -52,6 +52,25 @@ async def test_agent_store_only_owner_can_update_or_delete() -> None:
     assert await store.delete("private-a", "user-a") is True
 
 
+@pytest.mark.asyncio
+async def test_delete_builtin_only_targets_builtins() -> None:
+    store = MemoryAgentStore()
+
+    await store.ensure_builtin({"id": "builtin-agent", "name": "Built in"})
+    await store.create({"id": "owned-agent", "name": "Owned", "user_id": "user-a"})
+
+    # delete_builtin refuses to touch a user-owned agent
+    assert await store.delete_builtin("owned-agent") is False
+    assert await store.get_any("owned-agent") is not None
+
+    # delete_builtin succeeds on a built-in
+    assert await store.delete_builtin("builtin-agent") is True
+    assert await store.get_any("builtin-agent") is None
+
+    # And no-ops on a missing id
+    assert await store.delete_builtin("does-not-exist") is False
+
+
 @pytest.mark.asyncio
 async def test_update_builtin_only_targets_builtins() -> None:
     store = MemoryAgentStore()