Remove the baseboard and molding, using a flat pry bar.
Run the utility knife between the tiles if it looks as though caulk is between the tiles.
Spray the grooves of the tiles and along the top with spray lubricant. This will help break down the glue and make it easier to remove them.
Insert the putty knife behind one of the tiles on the end of the top row. Gently pry it off as you thrust the knife between it and the wall. Usually, getting the first tile off is the hardest. Once the tile is removed, immediately wrap it in bubble wrap to avoid possible injury.
Work you way across the wall and down, scraping the tiles off with the putty knife. Keep spraying lubricant to loosen the glue. As you remove each tile, wrap it in bubble wrap to dispose of it safely.