Ask someone to lend you a hand to remove your wall-mounted microwave.
Fold a towel and lay it on a nearby table or countertop. This will provide a "cushion" to protect the surface of the table or countertop when you uninstall the wall-mounted microwave.
Go to the main electrical panel in the house, basement or garage, and switch off the breaker that supplies power to the appliance. Go back inside and unplug the microwave.
Roll up the power cord and wrap painter's tape around it to keep the cord out of the way during the removal process. In addition, take the carousel out of the microwave, and then tape the door shut to prevent it from accidentally opening.
Locate the retaining screws on the bottom of the microwave that go into the mounting bracket. Ask your assistant to hold the microwave while you unfasten the screws, using a screw gun. Put the screws in your front or back pocket to avoid losing them.
Pull the microwave from the mounting bracket and set it on the folded towel temporarily until you are ready to dispose of the appliance or store it elsewhere.
Unfasten the screws holding the mounting bracket to the wall, using the screw gun. Turn the breaker back on after you are done.