When I went to va.com and looked for the status of my claim it said my claims had been "reopened" and that Disabled American Veterans was my VA Claims representative.
My question is that the DAV has never been of much help, so should I remove them from my case? I believe the VA has reopened these claims because of the Nemer Court decision. Although I am at 100% now and am 73 years old, I am concerned that reopening the case will cause my percent to decrease.
No, you don't need to do anything...in fact, you shouldn't attempt to interrupt what is happening. I'll assume you're Blue Water Navy or have similar circumstances regarding agent orange and VA is reviewing all those claims https://www.legion.org/veteransbenefits/252567/va-automatically-review-thousands-blue-water-navy-claims
The DAV isn't actually involved. They were notified at the time you were because they're your POA of record...that's SOP. The VA will conduct internal reviews of any findings and if they reach any conclusions that would affect you, you and the DAV will be notified so you can then decide what to do, if anything.
I would also suspect that this will not have any negative consequences for you. The review is actually looking for opportunities to award benefits that they may have missed in earlier reviews. Over time the rules are becoming more expansive...a good thing. You may come out ahead but there's little to no chance of losing anything.