I don't know of aguide, so I'll write you one!! They do come off fairly simply as long as you're careful.
Take the board out of the case & flip it over, I use a normal flat head screwdriver. Hold the screwdriver all the way down by the head, NOT UP BY THE HANDLE. Turn the flat head so you're looking at the edge & use it to push the center, usually gray, pins out through the front of the board. Once all 4 are out, then just squeeze the remaining, usually black, clips on the bottom of the bracket & push them through the board. Voila!! Be careful & take your time because we don't want that screwdriver to slip off & gouge the mobo possibly ruining it. And yes you can easily reattach it.