On the System Manager web console, click Elements > Messaging.
Click Subscriber in the left navigation pane.
Select a messaging system from the list of Messaging Systems.
Click Show List.
Select the subscriber you want to delete from the Subscriber List.
Click Delete.
The system displays a confirmation page for deleting the subscriber.
Confirm to delete the subscriber or subscribers.
Note:
You cannot delete a subscriber associated with a user through mailbox management. You can delete the user associated subscribers only through User Profile Management.