Not sure why you want to remove the quad rail after just a trip to the range. If grime get under there, you may want to just use something like gunscrubber (spray) to clean it....
Removing the quad rail is a bit involved if you don't have the right tools or knowledge. Lots of info on youtube about removing/ swapping the handguard.
I never have, and have owned the rifle for 3 years with thousands of rounds downrange.
-Rimfire Club#1097 -Florida Glockers Club#1097 -Black Rifle Club #1097 -Certified Glock Armorer
RIP John Noveske- 1976 - 2013