Go to my HD/HD+ CWM thread linked in my signature and make a bootable CWM SD per item 1a and use that to flash a plain stock zip from item 6. Follow that with a factory reset with CWM and you should be back to plain stock, ready for registration.
Sent from my BN NookHD+ using XDA Premium HD app
See my Nook Color Tips Thread here
and my Nook Color EMMC Partition Repair Thread here
and my Nook Color Updated CM SD Installation Instructions here
and my Nook HD/HD+ stock tips thread here
and my Nook HD/HD+ CWM Root Tools thread here
e.mote's Nook HD/HD+ Dummies Guide for installing CM10.1/CM10.2/CM11 here