You need to call Nintendo to unlink the NNID from your old 3DS, but this is going to be much harder. I tried doing this today and they brought up my ban, so I think they're on the look out for people making excuses .
God bless, it worked. I'm hesitant to delete my NNID since I've heard I won't be able to tie it to another console since I'm hearing conflicting info about not being able to tie your NNID to another 3DS since it assumes the NNID is still being used in the old console. Am I just screwed?
I followed this tutorial and my Eshop games disappeared from my Sysnand and emunand, I figured they'd appear again after I put my files back via a backup but they still don't appear. I spent long enough trying to search for a solution on my own so I figured I'd hit up this thread.