Just drill it out slowly with a drill bit slightly larger than the rivet. Don't let it heat up, or you might melt your armor. This is the most common way of removing rivets, and works well. Careful when almost done, as you don't want to enlarge the hole in the armor, either. Sometimes, you can drill out enough of the rivet, with only a thin amount left, to where you can just push it out with a pointy-something-or-other. A pair of needle-nosed pliers also helps to maybe bend things around sometimes. Hope this helps, buddy.
**edit** Oops. Sorry, LisaFett. It took me longer to type my reply than you took for yours 
(two fingered hunt-and-peck). Didn't know you'd already handled the answer.
