Press the bump with your finger to determine if it is hard or soft. Proceed to Step 3, if the bump is not solid. Wrap 150-grit sandpaper around a wood block, if the bump is hard.
Sand the bump lightly with the sandpaper. Use slow, smooth strokes until the bump is level with the rest of the drywall surface.
Cut an outline around the bump, using a sharp utility knife. Pry the utility knife blade underneath the bump and force the bump from the drywall. Fill the resulting recess with joint compound, using a drywall knife. Allow the compound 24 hours to fully dry.
Dip the drywall sponge in a bucket of warm water. Smooth down the ridges in the compound, using the coarse side of the sponge. Dip the sponge into the bucket to rinse it out frequently as you work.
Apply a second layer of joint compound, using a drywall knife. Allow this layer 24 hours to dry.
Smooth down the repaired spot, with a drywall sponge dipped in warm water. Paint the repaired section of wall to match the surrounding wall.