A couple things come into play. Torching itself is permanent on what gets torched. If you are torching a thick piece of SS, you can maybe sand down to original color but it will take a while. With a mod or atty, the metal is typically so thin that there is a good chance that no matter what you do the color will be altered all the way through. Perhaps not if you only get to the golden colors, but if you're into purples and blues the metal has likely been heated all the way through.
If you are really unsure or truly care about the mod you're thinking about torching, get a piece of stainless and test it there first. Also a little tip, if you want to be more precise use a lower flame on your torch. It will take longer but also much more gradually shift through the colors once approaching temp. HTH.