You can remove the flat head grub screw that fixes the armrest in position, thereby freeing the the j-hook/clip arm rest assembly to swing up or down on its metal support rod. Be warned however that removing this grub screw will be difficult - every screw on a TP is glued using a thread adhesive. A drop or two of acetone will usually dissolve the glue making it much easier to remove. You'll want to save the grub screw and obtain a new one as you'll have likely marred the head. In one arm board iteration, I had to do this to allow the arm to clear the lead-in groove as well. Just a slight downward tilt of the clip assembly did the trick, and the armrest is still perfectly functional as friction holds it nicely in place.