A jaw type bear trap put over outside button should deter unwanted
rings. Otherwise just a wire a switch by the door, down by the
breakers, or right next to the ringer unit. It would be even easier
to wire the swicth directly from the 18V transformer, which does not
pose a serious electrical risk. .

Oh, now I have to go buy a wolf-trap, weld it open, and nail it up
over my doorbell with a "no soliciting" sign...