Sand-textured paints are meant to hide minor imperfections and add a suedelike look to walls. This sounds like a great idea, but in the hands of people unfamiliar with these products, the result can often be a wall that looks patchy and feels harsh on the hands. There are several options available for removing these paints. Some are extreme, such as completely removing the Sheetrock, but others are less expensive. All involve patience and a dust mask.
Prepare your room by removing all furniture, if possible. Cover anything that remains with drop cloths. Protect your floors with drop cloths, and tape plastic over windows and doors. Push plastic underneath doors to seal the room off completely.
Find an inconspicuous spot on your wall or perhaps in a closet. Use the 6-inch knife to attempt to scrape off the sand paint. Scrape off large sand particles.
Put on your dust mask and work on the same spot, using heavy grit sandpaper and poles or an electric sander. This test area will determine how heavy your sandpaper needs to be for the rest of the room.
Repeat Steps 2 and 3 on the rest of the walls, starting with heavier sandpaper and finishing with lighter sandpaper.
Use drywall mud to lightly skim over areas where the wall may have small bubbles left from the sandpaper grit. Sand when dry with a fine sandpaper.
Prime the walls with two coats of a quality primer/sealer product. When dry, paint the walls.