How can we completely remove users / e-mail addresses from the database?

We have followed the steps to delete users that we found here:
How can organizers delete user accounts?
However, we want to completely remove those user accounts from the database.
How can we proceed?

(A German version of this article is available.)

ConfTool marks users as "deleted" if you delete them, but does not remove them from the database automatically.
If deleted users try to register again, they can't as they are still present in the system.

You can always "undelete" deleted users.
Please go to the "List of All Users" and set the filter option "Active and Deleted Users" to "Show only deleted users" to access the list of deleted users.
In the right column "Action" click on "Undelete User" to reverse the deletion.

If you permanently want to remove deleted users from the database, please use the option to purge them (see image):
Overview => User and Participant Management => Purge Deleted Users

Please note that this operation cannot be undone.

NB: The page ID is "adminUsersPurge", if you don't find that option in the menu.