If you want to unsubscribe from a LISTSERV list you can do the following.
Draft an email from the account you want to remove from the LISTSERV list.
You'll want to send the email to Listserv@listserv.gmu.edu
Remove the subject and all text from the body of you email including the signature.
Find the name of the LISTSERV list you want to unsubscribe.
In the body of the email type UNSUBSCRIBE listname.
You'll want to replace listname with the list you want to unsubscribe from.
For example: UNSUBSCRIBE SC-ALL-L@listserv.gmu.edu
Send the email.