Can a parent kick out her 22 yo son, and have the police enforce him not coming back.
He has no job, and a drug history

You will be better of in following the eviction procedures for your jurisdiction.

While I feel a parent should be able to do so, if he is that much of a problem, there are legal ways that he could punish you for not following the laws.

Save yourself future problems and do it legally.

OK, can you just change the locks and throw his clothes out the door, well I guess you can, can he then sue you for illegal eviction.

Best bet, evict him as if he is a renter. Then change your locks and don't let him back in.