I want to remove and replace my 1989 GE over the stove microwave oven. How do I remove the old one?

There should be screws in the cabinet above the unit.

They hold it from leaning down,much less up.

Take the top screws out,then leaning the unit forward to about 45% or so, lift,the base should be on a clip or bracket.

You should probably have help as these older units are rather bulky.

Let me know if my assumptions are correct.

KBC