My son lives in one of my homes he pays no rent - We have told him he was welcome to stay but then he wanted to move in his girlfriend -- we told him absolutely not if he wanted to live with her he had to move out - instead he moved her in and now she refuses to leave -

You can't evict her separately. Absent a specific written lease that prohibits additional occupants, your son has a right to have anyone he wants staying with him. Without a written lease, he is considered a periodic tenant. Therefore you can give him 30 days notice that you are terminating his residency. Which means his guests need to leave also.