If the Jehovah Witnesses come to your door and you don't want them there just either don't answer the door and wait until they go away or just open the door and politely say no thank you.
Say please just leave as I do not want you here on my property and please do not come back.
Let them know that if they do come back that you will report them to the police.
You have every right to keep Jehovah Witnesses off your property if you do not want them on your property so just tell them that you do not want them there.
I had to once call the cops on some Jehovah Witnesses that came back after I told them no.
I'm not religious in any way but have no issue with others being religious but they should respect my and everyone else's wishes as well.
If they are asked to leave and not come back that is what they should do.