Option 1: use the ListServ subscription management page.
Option 2: use email
For subscribers accessing their email through software (Outlook, Mail, Thunderbird, mobile devices, etc.): Generate an unsubscribe request.
For subscribers accessing their email through a website (Princeton Webmail, Gmail, Hotmail, etc.): send an email to listserv@lists.princeton.edu with this content (and only this content):
UNSUBSCRIBE weeklybulletin