How do I clear or delete a queue?
drush has no option to clear queues, there is just drush queue-list and drush queue-run. However, you can use it to delete the corresponding queue records from the database:


Use drush queue-list to find out the name of the queue you want to clear. In my case, it is message_subscribe.
Use a command like this, replacing with your queue's name accordingly:

drush sqlq "DELETE FROM queue WHERE name='message_subscribe'"

Confirm with drush queue-list that the queue in question now has zero items in it.


This solution is quite similar to @batigolix's, just that it clears a specific queue instead of all queues.

Careful. Like @batigolix said, take care not to lose data! This solution might not be for a production environment …