The set of permitted miners for a block is defined by the state of the blockchain at the end of the previous block. So if you have a block in which the last miner is revoked, then there is no way for any new blocks to be added without rolling back the chain. This is (intentionally) a little tricky but can be achieved by doing this on each node:
pause mining,incoming
setlastblock [hash or height of block before the one where the miner was revoked]
clearmempool
resume mining,incoming
Make sure you have run clearmempool on every node before running the resume command on any node, otherwise the mining revocation transaction can be redistributed again over the peer-to-peer network. Note that this will lose all transactions from after the block you rewound to, not just the one that caused the problem. If you need to be more selective, use the command below instead of clearmempool on every node:
setruntimeparam bantx [the txid in which miner was revoked]