The worst place for a MW is over the stove. They're horrible for venting. Better to get a regular MW and a decent vent.

And if your stove is gas, it's even worse.

Use a small prybar and gently remove the molding and it should come right out. Any remaining nails in the molding pull them out from behind or break them off (don't try to bang them out)

This is what you need available at home depot or you can order on amazon.

https://www.homedepot.com/p/Anvil-9-1-2-in-Pry-Bar-PB1-ANV/309996814

1. What are you going to do about the two blocks attached to the bottom of the upper cabinet? Generally, its expected that the surface of the cabinet be flat so the top of the oven can rest against it.
2. What is the height of the particle board above the tile on the rear wall? You'll attach a mounting plate to the wall which will support the rear of the oven.
3. Is the height of the new oven equal to the length of the red arrows? How will you swing it up into position even after you remove the bottom molding as the width of the opening is not the same bottom-to-top?

Not all 30" ovens are the same height. They range from about 14-1/2" to 18".

The prybar GN Builders suggested worked like a charm. It was a tight fit but we were able to get it installed. Thanks!!