Check with your state, municipal regulations, or maybe your lawyer.
Say you want them out by X.
A couple days after X, throw them out. I wouldn't send reminders or anything.
I'm petty. I would say nothing at all for months, throw them out, and never mention it. If he said anything after that, animals got into the garage and chewed things up; there was a break-in and stuff was vandalized when they couldn't get into the house; water damage is always messy; a box of cleaning rags caught fire and there was smoke damage. (Sounds unlikely, but the house across the street was totaled when the rags one resident used refinishing furniture in the basement caught fire.)