Unplug your microwave from the outlet if you have a countertop microwave. If you have a built-in microwave, turn off the power for that area of your kitchen. Remove the turntable from inside the microwave if you have a countertop microwave.
Turn the microwave on its back, and use the putty knife to pry off the cover on the bottom of the microwave door. Do this carefully to avoid damaging the plastic. Use either a Phillips screwdriver or a flat-head screwdriver to remove the screws by turning them counterclockwise. Set the microwave back in an upright position.
Pry off the cover on the top of the microwave door carefully, using your putty knife. Once the cover is removed, the screws holding the door in place will be visible. Remove the screws.
Lift off the microwave door.