Its probably brazed with brass (though I put my braze ons with silver) and trying to rip them off, will probably result in a damaged downtube. I'd leave them put, or take a grinder and grind it down.

Torching it will totally mess up your paint. I'm converting a frame now to a single speed (putting in track drops and removing all the brazeons) and the torch does wonders to the paint. Luckly my customer is getting it repainted and i dont have to worry about it.