If you need to shave, you'll want to use a razor. It's a tool that's made for removing unwanted hair.
There are straight razors (the old-fashioned kind that barbers sometimes use), safety razors for shaving faces and legs, and electric razors that use spinning blades to trim beards or shave heads. A hair stylist also might use razor as a verb: "Let me just razor the ends and we'll be done!" Razor comes from the Old French raser, "to scrape."