Solved, unfortunately you should do all the process in the following:
1) Back to stock using touchformatter see
http://forum.xda-developers.com/show....php?t=1475613
2) Register again with your old account
3) Deregister (you should do 2 and 3, on the contrary B&n recognize the nook is registered to another user)
4) Register with the new account
5) Root again from scratch
Really not so complicated as it seems, but next time I will register the nook with a secondary gmail account, so I can change my password and give the account to the new user.