Trying to restore iPad and old Apple ID password is required that doesn't exist
I have been trying restore my Mums old iPad to sell it. I have connected it to itunes and gone through the restore and reset but her old Apple ID is still coming up and asking for the password. This Apple ID does not exist anymore, nor does the email that it was associated too so I cannot get past this stage to remove it from the iPad. I seem to be stuck in an impossible loop of not being able to remove the Apple ID from this iPad so I can sell it. Please help!
iPad 2