title: Stopping/Purging Periodic Tasks in Django-Celery
body: <p>I have managed to get periodic tasks working in django-celery by subclassing PeriodicTask. I tried to create a test task and set it running doing something useless. It works. </p>
  
  <p>Now I can't stop it. I've read the documentation and I cannot find out how to remove the task from the execution queue. I have tried using celeryctl and using the shell, but registry.tasks() is empty, so I can't see how to remove it.</p>
  
  <p>I have seen suggestions that I should "revoke" it, but for this I appear to need a task id, and I can't see how I would find the task id. </p>
  
  <p>Thanks.</p>