Fix: launch an agent. (#13039)

### Type of change

- [x] Bug Fix (non-breaking change which fixes an issue)

Author: KevinHuSh

api/apps/canvas_app.py

@@ -633,9 +633,20 @@ def get_session(canvas_id, session_id):
         return get_json_result(
             data=False, message='Only owner of canvas authorized for this operation.',
             code=RetCode.OPERATING_ERROR)
-    conv = API4ConversationService.get_by_id(session_id)
+    _, conv = API4ConversationService.get_by_id(session_id)
     return get_json_result(data=conv.to_dict())
-    
+
+
+@manager.route('/<canvas_id>/sessions/<session_id>', methods=['DELETE'])  # noqa: F821
+@login_required
+def del_session(canvas_id, session_id):
+    tenant_id = current_user.id
+    if not UserCanvasService.accessible(canvas_id, tenant_id):
+        return get_json_result(
+            data=False, message='Only owner of canvas authorized for this operation.',
+            code=RetCode.OPERATING_ERROR)
+    return get_json_result(data=API4ConversationService.delete_by_id(session_id))
+
 
 @manager.route('/prompts', methods=['GET'])  # noqa: F821
 @login_required