If the guy is skating by on your previous approval you have to actually do something to let the landowner know he is no longer welcome.
That would make it uncomfortable for the landowner. If you brought the guy in and the landowner gave him permission, you can't ask the landowner to confront the guy and tell him he's no longer welcome. I think you'd have to be the one who does it. I might not even tell the landowner. He might get irritated at the whole situation and kick you both out and not permit anyone anymore.