To do this, you can purchase an inexpensive snake at a local store (about ten dollars). Run the snake down the drain and try to snag the hair with the special end, then pull the hair our. After doing this a couple times, pour in some drain cleaner to flush it.
You will need a snake or there are certain industrial strength drain cleaners that will get it done. The snake is the best way and you can get one at the hardware store.
My experience with getting out hair from the bathtub drain is to put a "snake" line down the drain. The snake that I am talking about is not literal but the nickname for a metal flexible pole you stick in to pull any debris out. It works!!
If the hair can be seen then normally you can reach in or use something a few inches long and slender to pull it out. If not, you may need a snake. I snake is a long cable with a handle on the end. Its purpose it for unclogging