I have found that some microwaves, and other gear
, are mounted with keyhole metal plates that friction fit to screws in the bulkhead or cabinets pace. Place a two-by-four horizontally across the bottom of the microwave, then alternately tap each side of the two-by to lift
the keyhole piece above the support screw. Be careful as the unit is heavy, and will now be totally unsupported, causing potential damage.