Repairing a broken tile on the floor or wall requires removing the grout around the damaged tile. Old, crumbling cement grout should be replaced before the water finds its way behind the tiles and creates additional damage. Finally, your grout may become infected with the mold that no amount of cleaning can remove; Just removing and replacing the grout will solve the problem. Whatever the reason you have to remove the grout, choose a technique that works for you and the situation.
Preparation
Protect the surfaces surrounding the area where the grout is to be removed. Tape of a plastic tarp on any surface where the old grout could fall. Use Painter's tape to protect the edges of the tile. Wear protective goggles and a dust mask. Regardless of the technique you choose to remove your grout, chips can fly into your eyes and grout dust cannot be avoided.
Sierra Grout
A hand saw Grout employs a blade of carbide-edged grain that cuts through the old tile grout. Keep the flat portion of the blade against the grout as a saw movement is used to remove grout from between the tiles. Depending on the grout strength, removing it with a grout saw may be difficult. Have several spare blades on hand if you intend to remove all grout from the tile area.
Rotary Tool Sharpening
Use an electric rotary abrasive tool equipped with a bit of grout to remove grout from between tiles. Keep the abrasive tool in your hand as if it were a pencil for more control. Slowly move the tool down the grout lines, being careful not to touch the edges of the tile. You may still require a grout saw around the corners and edges, depending on the hardness of your tile.
Hammer and slotted screwdriver
Remove grout with hammer and flat-tip screwdriver or 1/4-inch wood chisel. Place the chisel or a screwdriver against the grout and gently tap a hammer. Work slowly, always position the chisel or a screwdriver away from the tile. This method can splinter or break your existing tile if done incorrectly. Use this technique only as a last resort.
Clean
Use a toothbrush to scrape grout residue from between tiles. Use a vacuum cleaner to remove the smallest bits of cement grout and grout powder from the mosaic surface. Clean the tile surface and the space between the tiles with a soft brush and water. Allow the tile surface and grout space to dry before regrouting the area.