This addon should help you to check if you still need your customer users. In this version, it supports only the OTRS DB as customer user backend.
After installation, the admin gets a new item in the customer section: "Customer User Check". In that dialog a list of checks can be selected and all customer users that satisfy all selected checks, will be listed on the right.
You can now select the customer users and delete them from the database.
You can extend this addon on your own: You can create new checks and you can create your own deletion module
The check module needs two methods:
Run method gets a list of customer ids that passed the checks before and it has to return those that passed this check.
The deletion module is responsible for deleting the customer users. By default this module supports only the OTRS DB as a customer user backend.
If you've configured an ActiveDirectory or a LDAP backend, the user configured in OTRS usually doesn't have the permissions to delete any LDAP entries. That's why this isn't supported. But you could write your own Deletion module to delete the users from your LDAP.
Or when you have established any other deletion process, you could implement it for this addon.
You can use the code of this addon as an example: https://github.com/reneeb/otrs-CustomerUserCheckAndDelete.
If you need any help with this addon, please contact us at firstname.lastname@example.org