how to remove task from celery with redis broker?

The simplest way is to use the celery control revoke [id1 [id2 [... [idN]]]] (do not forget to pass the -A project.application flag too). Where id1 to idN are task IDs. However, it is not guaranteed to succeed every time you run it, for valid reasons...

Sure Celery has API for it. Here is an example how to do it from a script: res = app.control.revoke(task_id, terminate=True)

In the example above app is an instance of the Celery application.

In some rare ocasions the control command above will not work, in which case you have to instruct Celery worker to kill the worker process: res = app.control.revoke(task_id, terminate=True, signal='SIGKILL')

I know two ways of doing so:

1) Delete queue directly from broker. In your case it's Redis. There are two commands that could help you: llen (to find right queue) and del (to delete it).

2) Start celery worker with --purge or --discard options. Here is help:

--purge, --discard    Purges all waiting tasks before the daemon is started.
                      **WARNING**: This is unrecoverable, and the tasks will
                      be deleted from the messaging server.

I just had this problem so for future readers,

http://celery.readthedocs.org/en/latest/faq.html#i-ve-purged-messages-but-there-are-still-messages-left-in-the-queue

so to properly purge the queue of waiting tasks you have to stop all the workers, and then purge the tasks using celery.control.purge().