removed tasks in beat_schedule still in task list

Hi all, I used django-celery and django-celery-beat to set several periodic tasks. After I deleted some unused tasks in beat_schedule, I found they are still in task list and I got error message said “Received unregistered task …”.

How can I remove unused tasks in celery list? I tried to use celery -A forest_dashboard purge and re-install django-celery neither works.

I deleted relative records in database table django_celery_beat_periodictask. Now it works. Thanks~