cut the grout line between the tile then ,after that you will have to break the frist tile to get a start then use a good puddy knife to remove the rest of the tile be careful some tile may break , you may wish to match your old tile with some new, if you can't find it off set with a differnt tile color don't worry about any holes in dry-wall the new adhesives will fill them or patch with dry wall mudd ,set new tile and re-grout