Silverbucket's instructions and documentation has moved to a new address:

One should never delete anyone from the system – and deleting someone is only possible by our support team. Deleting people can break the history data so think twice before asking our support to delete someone. However, you can make people inactive or active in your Silverbucket environment. This action is done on person’s dashboard or in the admin page.

Passive users can still be viewed witihin the interface if so wanted but making a user account passive and stealth will hide the account from all the views.