No you don't need. If you tell the university that

you are leaving, they probably will withdraw your 140 from CIS.

If your boss corporates, univerisity ISSO won't know that you're leaving and will keep the process going. After 140 is approved, you can safely leave after 180 days of 485 pending.

Approved 140 will send to the univerisity, you can have a copy. And you do not need it right now because your 485 is already filed.