The article doesn't really tell us what the contract terms are, though. Just because the city voted to cancel the contract doesn't mean it ends immediately and Flock has to come remove all the cameras upon request. It's very likely the contract has a fixed term, and cancellation really just means they're not going to renew it at the end of the term. If that's the case, you can't charge them with crimes for using infrastructure that the contract permits them to use.

Still terrible that Flock isn't responding to them, and of course even if they intend to hold the city to the contract in terms of expecting to be paid for the full duration, they should still honor the request to shut off service.