Why do you want to remove the hand guard?
There is a kit here;
Barrel Vise Jaws and Barrel Nut Wrench (Pro) for Smith & Wesson M&P15-22 - COMBO [BVJ-1 and BNW-2-A - COMBO] - $47.00 : Tacticool22, Tactical .22 Rifle Parts and Accessories
that you use to remove the barrel nut so you can remove the hand guard.
If you want to put a free float hand guard on, there is another kit for that.
If you want to put any 2 piece hand guard on, there will be a kit for that in about a month.