There is a special type wrench that you need to remove the stem. It can usually be purchased fairly inexpensively at a hardware or home improvement store. You will need to determine what size the valve is or the wrench may come in a multi-pack with more than one size. This wrench is about 4-6 inch's long and has a hex-shape on either end. The end usually has two holes on both ends to pass a screw-driver or pry type device through in order to turn the stem and remove and reinstall the faucet.
