How do you stop a cat from peeing?
First, take the cat to the vet. If there are no urinary tract or otherwise problems, place litter boxes in places where he/she should not be doing his wee-wee or poo-poo. If you can't do that (like if your cat is doing his/her business where you have to walk), make the place where he's going as unattractive as possible, and the spot where he's supposed to go as attractive as possible. Put a rug under his litterbox, and don't clean the box too often. Turn the place where he's going into a feeding station; he won't do his business near his food. Place the litterbox in a quiet, easily accessible place (young kittens and senior cats don't like going up and down stairs a lot). Remove every bit of evidence of his urine from the place he's been using (don't use cleaning products containing ammonia, they'll smell like pee to the cat and he/she will attempt to cover it by peeing again), also, you can temporarily put aluminum foil in the place where the cat's not supposed to go (they don't like the sound or feel of aluminum foil, so they'll avoid the area. Also, spraying lemon scent will repel a cat.
Seeing as the answer above does not really answer the question:
Urinating is a bodily function all mammals need to do to get rid of excess liquid and other waste and potential toxins. You can not stop a cat from peeing, but if your cat has a sudden change in toiletry behaviour it is best to take it to the vet as soon as possible.
Firstly, the question is extremely vague. The range of meanings covers everything from "How do you plug your cat's urinary opening" to "Why has my cat's toiletry behavior changed." Secondly, it's extremely difficult to answer because of its generalization.
~Vampyria--I partly agree with you, but there is no right or wrong answer to this question unless the asker specifies.