Unplug the microwave.
Ask a helper to hold on to the bottom of the microwave.
Unscrew the screws from the cabinet part way by turning them counter-clockwise with a screwdriver. Continue to unscrew them until they are no longer inside of the top of the microwave.
Pull the screws up through the cabinet and set them aside.
Ask your helper to lean the microwave slightly forward.
Place your hands at the bottom of the back of the microwave. While your helper still holds the microwave in the front, push up on the back of the appliance until the microwave lifts up out of the tabs on the metal frame on the wall.
Set the microwave down on the counter or floor.