Help deleting session cookies from Safari

I'm on Safari 6, and need to delete session cookies from Safari -- altogether, not just for the current tab.

In the Develop > Web Inspector, you can see session cookies and delete, them, but only from that particular tab. e.g. if I have an authentication cookie and delete it from a tab, I can open a tab, and be successfully authenticated to the site I deleted the cookie for.

I understand I should be able to delete or modify the cookie via Javascript through the quick console, but could use a little help on the syntax to invalidate or delete the cookie

Thanks in advance!!
Avery