Is there any treatment for hairy nevus.?

Often no Rx best. It depends on the case. Even good plastic surgery is likely to disfigure. When these are excised, they tend to grow back because they originate in the deep nerves and are resupplied with cells from there. Ask ten of your real friends whether to try to remove it or leave it alone. You'll be surprised. Invite folks to touch it for good luck.
Surgery. . Laser does not work well for these. Surgery is usually the best way to get rid of these.