If he's a month-to-month tenant with no written rental agreement, then you would evict him as a month-to-month tenant with no rental agreement. You would provide proper notice to terminate his tenancy based upon the facts of the case. If you try to rush things through by issuing an improper notice and he objects in court, the court will make you start over. You had a quid pro quo agreement, so even if he stopped doing the work he was to perform in exchange for 'free rent' he's a tenant. You will want to make sure that the notices you give are in proper form, such that they will be recognized by a court when you file an eviction action.