Turn off power to the microwave at the circuit breaker
Unplug the microwave if the plug is accessible
Remove the mounting screws from the upper cabinet
Support the microwave from below with another person
Remove the bottom front mounting screws if present
Lift the front of the microwave slightly
Slide the microwave off the rear wall bracket
Lower the microwave carefully
Remove the wall bracket if needed
Remove any remaining screws, anchors, or trim pieces