Starting at the edge of the wall place the blade against the mastic and give the handle a solid tap with a hammer.
How to remove a single wall tile.
Grout is essentially a fine cement.
To remove wall tiles start by heating up the grout between the tiles with a blow dryer so it s easier to remove.
Tap the end of the nail set with a hammer to shatter the tile and pry the pieces off with a chisel.
Position the tip of a nail set against the tile at the cracked or chipped area.
Push the grout into the joints at different angles to fill them all.
Use a utility knife to score grout joints around the cracked tiles.
The wider the grout gap between the tiles is the better.
Next use a chisel and hammer to pry the tiles off of the wall.
Move the nail set.
Using the masking tape cover the adjacent tiles around the target tile.
Remove the painter s tape from the surrounding tiles.
Protect work area with canvas drop cloth.
In most cases the knife will slide under the tile and by simply lifting the handle up the tile will pop off the wall.
Clear the surrounding area remove dirt and soap scum and put down the dustsheet or other protection.
In this video this old house tile contractor joe ferrante explains how to replace a wall tile.
Then use a utility knife or rotary grinder to scrape away the grout until the spacer lugs between the tiles are visible.