Relief from nocturnal emission?

Fact of life. If you are a normal, sexually-mature male and do not masturbate or have a partner, you will have wet dreams. One of the cults teaches that these are unhealthy. This is a lie intended to frighten teenagers. I personally know one pastor who left the cult rather than teach this. Being a man is difficult enough without having this frightening and false put into your head.
Trying to stop them? Nocturnal emissions (of semen) are normal for human males, which means it would be unnatural to try to stop them. A primary care doctor or urologist can evaluate to see if the emissions are unusual (such as too often, too much semen, wrong age group, etc...) and decide if there is a problem. Meanwhile, one can choose some soft, absorbent underwear.