I own a house and am renting a room to someone. There is no lease and he pays rent on a month to month basis. The problem is that he hasn't paid me rent lately. How can I legally get him out as quickly as possible? I live in Maryland

Give him a notice to quit Notice to quit Free Form order for
Maryland 9 day eviction (5 days to appear in court, then 4 to vacate)
I think you have to go through the court.
You can not just tell them to leave