@Anonymous Coward and Don Sinclair
You could always just tell the truth and the next time Witnesses come to your door, tell them you're not interested and preferred not to be called on again. If you don't want to do it face to face you could even look up the phone number for a local Kingdom Hall and tell them your address and that you don't want to be called on again. It's that simple. Running and hiding while they're at your door never solves anything. Neither does being mean.