The Patron Deletion Tool won’t delete my patron, why not?
Patrons with items checked out or on hold cannot be deleted until the items are checked back in and the holds are cancelled.
As well, if the patron’s home library does not match your home library (or one of your branches) you will be blocked from deleting the patron. You can edit the patron’s account and update their home library to match yours in order to delete the patron.
More information on deleting patron accounts can be found here.