I hate doing this. Burning them off is easy, but my torts never seemed to like the cactus as well. They weren't over the heat long, but must have been long enough to make them a little less desirable. Scraping them off with a knife wasn't as easy as I thought it would be. Today I had a bunch to do. I tried a rasp/zester. (See pic). This is my new go too, so easy and I feel did the best job. Was very easy to do the edges too.