code: def delete_account(self, data):
          
          error = False
          msg = ""
  
          username = self.user_manager.session_username()
  
          # Check input format
          result = self.database.users.find_one_and_delete({"username": username,
                                                            "email": data.get("delete_email", "")})
          if not result:
              error = True
              msg = _("The specified email is incorrect.")
          else:
              self.database.submissions.remove({"username": username})
              self.database.user_tasks.remove({"username": username})
  
              all_courses = self.course_factory.get_all_courses()
  
              for courseid, course in all_courses.items():
                  if self.user_manager.course_is_open_to_user(course, username):
                      self.user_manager.course_unregister_user(course, username)
  
              self.user_manager.disconnect_user()
              raise web.seeother("/index")
  
          return msg, error
docs: Delete account from DB