Laws ons evict or vacate do I need a reason

DO they have a written lease that's still in effect? [Yes] Or are they month to month currently? [No]

If they still have a valid lease... you do need a valid reason that shows they are in breach... if they are month to month you just give then a written notice 30 days in advance they will need to leave at the end of the month, you don't need a reason. I'm assuming you aren't in one of the few areas that have whats called "rent control"