How can you stop wet dreams?

Well you can't really. It's your hormones and subconscious being in control when you sleep. It's all normal and all men and women have it. During puberty it's extra intense because of all the hormones.

There is nothing wrong with wet dreams they are a natural way for the body to release sperm.

You cannot put a stop to wet dreams, also known as "Nocturnal Emissions", but by masturbating before going to sleep you remove the sexual tension that has built up during the day. This will lessen the chance of having one.