Cover the floor and furniture in the room with the drop cloth. Open all the windows in the vicinity. Place the face mask over your nose and mouth.
Attach the 60-grit sandpaper to the belt sander and plug the sander into a power outlet.
Hold the belt sander with two hands and turn it on. Move the belt sander over the wall in a circular motion to remove the textured paint. Use the ladder to reach high areas of the wall to avoid lifting the sander above your shoulders. Remove the largest bumps and ridges with the sander.
Change the sandpaper when it gets clogged with paint. Run a wire brush over the belt sander to remove the paint clogs.
Apply wallboard joint compound with a trowel in a thin layer to even out the wall. Allow the compound to dry.
Sand the wall smooth with 100-grit sandpaper by hand.