How do you deal with JW's?

These days JW's (Jehovah's Witnesses) have been knocking on my doorstep, the usual preaching and on the side, they want me to join their religion. But I'm already a Catholic, a Christian as they same as they are. So I want ask how do I respectively ask them to stop, because I'm very comfortable with my own religion and beliefs, so they could stop coming to my doorstep every waking moment.