Not easily, and because the style or angle of the old one isn't available anymore.
A properly built lugged frame will have pins driven through a hole in the tube and lug to maintain their position while brazing. So, to salvage a lug, you not only have to melt/remove the braze, but find and remove those pins too.
A lot of lugged frames don't use the pins. Seems a lot of better builders these days use them, but in older books quite a few builders regarded them as a bad idea, likely to build in stresses. Also they take extra time to do, so factories that churned out lugged bikes would have avoided them if they could. Still a good point that one needs to keep a watch out.
In this case, what is the questions? Are you asking whether the bike can survive lug removal. Sounds like you are preserving the frame for a project, you can't remove those lugs. Some people have successfully removed lugs to practice with by tearing the frame appart. If you did that, and weren't planing on keeping the tubes you could cut them off and look down them to spot any pins. Leave enough tube to hold onto. It takes more heat to take a frame apparts than to melt the original braze.