Thanks for all the advice, the project was on hold and about to get started.
I borrowed a multi tool from my B.I. but he doesn't have a the right blade so I am checking for blade cost now, if the cost is high then I will buy my own multi-tool it just seems like a good tool to have. I also borrowed his grinder.
I can't leave the brick material on the wall, the MW already is sticking out too far (if installed) and the rough finish on the bottom edge would look terrible. You should see how the electric outlets look, awful!
If the material doesn't come off clean, and I am almost 75% sure there may be patches that when tearing away from the drywall will take huge chunks of drywall, thus possibly forcing me to cut out the entire section and patch with new drywall.