I started with removing the spring awhile ago. But it just didn't flip nearly as well as my other unassisted flippers. The detent was a bit weak so I found it worked best with the thumb stud. Except that the flipper tab was in the way when using it.
I used the dremel cutting disc so rather than grinding it down I just made one cut, followed by some hand finishing with my sander. Most important thing was managing the heat, but I found that as long as I was holding the blade in my hand while doing the work, I had instant feedback if the blade was getting warm, so I just gave it a dunk in a nearby bucket of water whenever it started to heat up.