Use a chisel and a hammer to crack existing tiles. Once cracked, remove the tile in pieces, if it does not fall off automatically. Chisel off remaining pieces. Beware not to gouge the wall too deeply, or you may create an uneven surface. If the resulting wall is very uneven, you may want to re-plaster it. It is best to hire a professional to plaster the walls. If you are installing wall tile in a bathroom or other wet area, use cement fiberboard on the surface before you adhere tile.
Take your tile to the home improvement store to try out glue. Different ceramic tiles require different types of glue. You do not want your glue to discolor the tile.
