Acces control remains active when you remove a vocabulary from PbT

Steps to reproduce.

Set a vocabulary in PbT configution page
Set allowed terms in users form
Set allowed terms in articles
It works ! So far so good

Now go to PbT configution page and unset the vocabulary.
Actual result: Permission are unchanged.
You have to manually unselect allowed users in all terms of your vocabulary (you cannot unselect all in users form).
or uninstall Pbt (could be an issue if you have sereval active vocabularies and want to unset only one)
or remove permissions in database via an sql query.
Solution:
This should be perfomed automatically from a form.
By example:
when you unselect a vocabulary a hidden form should appear:
Do you want to delete all permissions rules based on this vocabulary? YES NO