Restore User feature is available since KuberDock 1.5.0.
If you are creating a user with an email that has already been registered in billing system and has been deleted from KuberDock, then you are able to restore that user in the process of creating. Once you add email and other necessary fields and click Save, then if such email is already exists, then you will get a pop-up:
If you click Yes, Restore then a user will be recovered from database. Recovered user becomes active after restore.
If you click No, Thanks, you will be redirected to the users' page without creating a new user.