Personally, here's what I'd try: With help, one person hold the bird, legs away from that person. Take a pair of pliers, gently grab the spur at the base, close to the leg, pliers parallel to the leg. Hold the leg still with your other hand. Gently (just enough squeeze pressure to hold it...not too tight) "twist" the spur and see if it pops at the base. If it does, it should slide right off, like a sheath on a knife. It may bleed a tiny bit, can use some cornstarch, or just pat it dry, or hold pressure for a bit, and it should stop.
If it doesn't pop off easily, then no harm done, explore other options.
If it works, there will be another smaller, soft spur under it, that will harden. Process can be repeated later on.
