You an do whatever yo'd like with the draw stop. You can take it off if you'd like. The only thing that really changes is that the bow will feel a little more spongy at the wall. In other words you'll have a little softer valley. Try it. You might like it.
That's how I shoot mine and I like the feel. Maybe that's because I started shooting compounds before the advent of solid walls and/or draw stops. Back when most bows had a valley about an inch in length.
Another thing comes to mind here. Once you draw the bow you should use back muscles to hold the bow. You should never creep forward or you'll experience just what you are now. You creep forward a bit and the bow wants to take off on you. OK, so you creep a hair. Many of us do. The cure to this is to shorten the draw length of the bow just a touch---maybe 1/4". This might be another reason you started hitting your arm. These are two common maladies of too long a draw.
Another thing that contributes to hitting the arm is improper grip.
Something you might want to read is a book entitled "Core Archery" by Larry Wise.
If You're Not Living on the Edge You're Taking Up Too Much Space
Martin/Rytera Staff Shooter
PSAA Life member, UBP Life member
PADI AOW Diver