Remove anything stored inside or on the toothbrush holder, such as toothbrushes or cups.
Close the sink drain, if present, beneath the toothbrush holder. This will prevent debris from clogging up the drain.
Spray bathroom cleaner on the grout around the tiles and scour off any mildew or mold with a nylon brush. Wipe the area clean with a towel.
Use a grout saw to remove the grout around the edges of the ceramic toothbrush holder. If you have a rotary drilling tool equipped with a mortar or grout cutting blade, this can also be used.
Insert the edge of a putty knife or chisel in between the edge of the toothbrush holder and the neighboring tiles. Gently press down on the chisel or putty knife until the ceramic toothbrush holder begins to loosen from the backer board or drywall.
Work your way around the edges of the toothbrush holder, prying it away from the wall, as you go, until it comes loose.