Wa alaikum salam,
He has to fast and stop watching things that provoke his desire and to surround himself with practicing Muslims!
The way out is repenting sincerely, feeling deep remorse. Getting married, or fasting. And putting the things in your life straight, such as getting rid of bad company, quit wasting time, refrain from sins such as watching movies, TV, Internet and seek the pleasure of Allah by learning the deen, and doing good deeds, constantly. Allah doesn’t burden a soul beyond what it can bear and masturbating is a sin that one can stay away from like the millions of Muslims!