If you can get away with it you may want to patch over the old d-ring with a new one, its not holding air and you may do more harm than good by trying to remove it if the bond is strong. I would not normally say patch over a patch but packraft rubber is not the strongest stuff ever made. You may just want to try and remove the outside second layer on the patch and leave the inner one attached to your raft.
To remove:
If you used Stay-bond glue, or the PVC clifton equivalent, use M.E.K. as a solvent for the glue. I assume you also used M.E.K. to etch the boat and patch to accept the glue, the same stuff is also the solvent for the glue. But be very carefull, M.E.K. is not only a carcinogen that flows directly through your skin and into your blood stream (use gloves and check them for holes regularly. M.E.K. eats rubber gloves also) it will also eat the rubber on your packraft if you use too much or soak it for to long. Apply a little bit, with a Q-tip or small brush and have a rag to catch the extra runoff, and start working the glue bond by slowly separating it. Every time you get it a little bit apart it may be necessary to apply a little more M.E.K. Be careful the patch/ is thicker than your boat and you do not want to rip your boat or eat all the rubber away.
This removal technique is from my experience working with larger commercial PVC whitewater rafts. I have glued a fare amount of patches and d-rings to a few packrafts but have not tried to remove any of them. If someone else has come up with a better solvent or technique please speak up I`d love to hear about it.
P.S. As far as the NRS patch goes I have never owned a single NRS item that did not fall apart, shoes, patches, dry-bags, boats ext. Bad quality made in china. Get a Aire or Maravia D-ring they are made and stitched superior to anything made by NRS.
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