I'm not quite sure how celery works, but I suspect you want to purge a RabbitMQ queue (you're currently simulating this by deleting the queues and having celery re-create them).
You could install RabbitMQ's Management Plugin. Its WebUI will allow you to purge the required queue. This should also tell you which queue you're aiming for, so you wouldn't need to delete everything.
Once you know which queue it is, you could purge it programatically. For instance, using py-amqplib, you would do something like:
from amqplib import client_0_8 as amqp
conn = amqp.Connection(host="localhost:5672", userid="guest", password="guest", virtual_host="/", insist=False)
conn = conn.channel()
conn.queue_purge("the-target-queue")
There's probably a better way to do it, though.