Take it off!!
I am going to tell you a rabbit story which might make up your mind.
Years ago we got a new neighbour, came froma country where I guess pets are thought of a little differently, anyway he had a rabbit(had no kids) the rabbit lived in a wire frame with no top on the back lawn, he didn't feed it said it ate grass, didn't give it water said their was moisture in the grass, I might add he was an OK neighbour apart from the rabbit, no amount of nice talking would convince him that rabbits in Canada needed shelter, food and drink.. so we decided to do something ourselves..bad but it was for the sake of the rabbit, we went out after midnight, got the rabbit(we already had a home for it) and pushed over the pen thing. Next day he told us about the rabbit , we crossed fingers behind our backs and told him the coyotes had probebly got it, few days later he got another rabbit..same set up, we only waited a day or two, still puzzled the man couldn't understand it, again we said it would be the coyotes AND they come back to a food source..his rabbit keeping days ended then, he never got another one..extremes yes, but the rabbits couldn't help themselves....
Take off the collar, the cat can't do it itself!!
XX Jeannine