I kept the lower pair at the ends of the shelf since they may have some air-bag related purpose. But the uppers got in the way of cabinets. I completely removed the one on the passenger side and cut the back half off the one on the driver's side. If you search "black foam things" on this forum you'll find lots more info.
I took them off. Pretty easy to take out the clips with a hammer claw. I can't see what they are for unless it's for head protection? I have them sitting in my van now, will throw them out unless anyone here sees a good use for them?