CSD keeps a log over everything that a user does. This is to keep track of who has been involved in updating a Schematic.
Due to this one are not allowed to delete a user in CSD, as this will also delete important history. Instead a user or role can be set to
Expired, preventing them to show in the list. (If a user is created but never used for log in, it can however be deleted). This is done by the System Administrator in the CSD top menu: Database, administration, Users..., Person: Expired Date.
Tip: You can view the expired persons and roles by ticking off Show Expired Persons / Roles in the Person dialog.