Deleting users

Hello,

I'm trying to delete WS users (employees who have left the company, vendors we no longer use, etc.). For a number of them I can't delete them. They are only disabled instead. This is the message displayed at the deletion screen: If a user is referenced by workflows, tasks, issues, or any other object in WorldServer, then the user will be disabled instead of deleted. A disabled user may not log in and will not appear in user lists How can I track down the project/task/issue in which they are active so as to permanently delete them? I changed the password and logged in as one of our former employees. Projects assigned to me is empty, but I still can't delete the user.

Thanks as always in advance!