Remove the rack bar from between the cemented rack brackets by sliding the bar ends from the bracket holes.
Place a drop cloth on the floor at the base of the rack to catch any falling debris. Cover the surrounding tiles with masking tape to avoid scratching them with flying debris as you remove the cement. Put on a pair of safety goggles to protect your eyes from debris as well as a facemask to avoid inhaling cement dust.
Cut away any caulking that may be placed at the base of the cemented brackets as waterproofing with a utility knife.
Place a small chisel across the strip of cement surrounding the base of the rack. Angle the chisel slight, about 45 degrees, and strike the head with a hammer to chip away at the cement around the bracket. Remove all of the surrounding cement with the hammer and chisel until you can see the joint of the bracket against the surface of the wall.
Place the tip of the chisel into the joint between the bracket and the wall. Chisel out the cement in the joint as deeply as possible.
Switch to a prybar. Place the prybar into the joint and apply upward pressure, prying the bracket from the wall. There will be a layer of cement remaining against the wall after bracket removal.
Remove the cement layer with a rotary tool containing a carbide grout blade. Run the blade over the cement, slowly cutting it away from the wall until you reach the wall’s surface.
Remove the remaining thin layer of cement from the wall with sandpaper attached to a sanding block, or with a rotary sander.