Grasp the Multimaster tool in one hand and the lever on the top with the other. Lift the level until it extends fully toward the front of the tool body, and lies parallel with the tool.
Pull the holding pin from the head of the tool, and then place the grout blade onto the spindle located on the head. Push the holding pin back into the hole in the head until it clicks into place, and then close the level to lock the blade securely.
Hold the blade onto the grout surrounding the tile you wish to remove. Turn on the Multimaster to begin the blade movement. Push the blade along the surface of the grout, allowing the blade movement to cut through the grout down to the base of the tile, and opening the tile joint. Do this to all of the joints surrounding the tile.
Place a small chisel into one of the joints. Tap the head of the chisel with a hammer to drive the chisel tip beneath the tile. The farther you drive the tip the more the tile will wedge upward from the surface, until it pops free. Remove the tile.
Open the tool again and remove the grout blade. Replace it with the carbide rasp, ensuring that the rough surface of the rasp points away from the tool body. Secure the rasp in place and close the tool.
Place the rasp onto the surface of the thinset revealed when you removed the tile. Turn on the tool to begin rasp movement and sand through the thinset to the subsurface below. Brush away the thinset after removal.