You can exclude users who are not in your workbench organization.
We understand that you want to preserve the user information that you will delete, so the user is moved to a file list and the user is blocked from entering your work environment.
Enter the user management screen for your environment.
Select the user you want to remove from the system.
Add the username - "Inactive", to indicate that it is inactive on the system.
Click on the "Delete User" option at the bottom of the screen.
5. The user will now go to the file list at the bottom of the user management screen.