Administrators with the role of Server administrator can delete any administrator accounts.
Note: The siadm account cannot be deleted.
To delete an administrator from the Configuration Database
In the Scope pane, expand the connected Server, then expand Administrators.
Select Accounts to display the list of administrators in the Results pane.
In the Result pane, right-click the name of the administrator account that you want to delete.
Select Delete. You are prompted to confirm the deletion.