You may decide to remove a medicine cabinet from the wall while remodeling. Once you have removed the medicine cabinet, you will need to patch the large hole left behind. While the problem may look daunting, patching even large holes in drywall does not require a high level of skill. You will need to let the project sit overnight, but with some care in the finishing process, you will not be able to spot the location of the large hole anymore.
Cut the hole into a perfect square or rectangle with a drywall saw. Measure the height and width of the hole twice and cut out a piece of drywall that is the same size, using the drywall saw.
Press four drywall mounting tabs onto the edges of the cutout in the wall, near the four corners. Align them so the two spring tabs on each of the mounting tabs face away from the wall and not toward it.
Insert the new piece of drywall into the hole and press it firmly against all four mounting tabs. Drive two quarter inch drywall screws into opposite ends of each of the drywall mounting tabs, with a screwdriver. Drive one screw through the new drywall and the mounting tab and the other screw through the old drywall and mounting tab.
Pinch the two spring tabs on each of the four drywall mounting tabs using a pair of needle nose pliers. Apply enough force to the needle nose pliers that you shear off both of the spring tabs.
Apply strips of fiberglass-mesh tape over the seams between the new and old drywall and spread joint compound over the tape with a putty knife. Let the patch sit overnight, then sand the dried compound lightly with 100 grit sandpaper.