Restaining bathroom vanity cabinets is an inexpensive alternative to replacing them. It is even possible to restain over an existing finish, eliminating the need to strip away the old finish. This is done using a gel stain and the color changes produced can be dramatic. The alternative is to remove doors and hardware, then apply a chemical stain remover and use steel wool to remove the old finish. Sand the vanity to completely remove all traces of the old finish and clean with mineral spirits. Allow to dry and apply the new stain in your choice of colors. Apply with a sponge to avoid dripping down the sides of the vanity. Allow to dry thoroughly.