The NIPS for this doesn't currently have revocability. Messages are too ephemeral and there's no mechanism for knowing that all nodes have seen the revoke message.

The best we have is if the relay has seen the message, the message itself sets an expiration. So if you delegate signing to another key for 3 days, 30 days, whatever, any relay that has seen this delegation will accept messages signed by the key until the time-out. If it hasn't seen the delegation message, though, it will reject them.