Legal Question in Civil Litigation in Maryland

Hopefully you obtained a security deposit to protect you against this type of problem. If there is any way to lock him out you can do that since it would be considered a commercial lease. If you want to enforce the lease, you will have to take him to landlord-tenant court on a complaint for repossession (eviction) and back rent. Legally you can collect until the end of the lease, but you have a duty to try and re-lease the property to mitigate (reduce) your losses. But if you haven't tried reaching out to him yet, I'd try that first to see if it can be resolved amicably.