If a child deficated or urinated in a clroom after being told no what could be done to prevent it again?

Well the teacher is a rotten load imo and the parents need to have a meeting with the school asap. It's unacceptable for a teacher to wield power like that on a child. It is possible the kid is very shy and may have problems the teacher is not aware of. In any event . . the parents need to have a meeting with the school and get to the bottom of it and put them back on their heels and make sure they're a little more objective in the future.