nope, nope, nope - no drywall repairs at all.
The old box, if original, was likely nailed to the stud next to the door. You can use a hacksaw blade (or a fein multitool) or something similar to just cut the nails. Then pull the box out. Trace the new remodel box to the drywall and cut the new opening (I assume you are going from single gang to double).
You can go back and do that, you only repairs would be where you anchored the wiremolding into the drywall.