Assuming that the list’s name is LIST_NAME, go here
and at the bottom you will see
“To unsubscribe from LIST_NAME, get a password reminder, or change your subscription options enter your subscription email address:”
Enter your email that registered the mailing list and click the button. Finally, on the next page click the “Remind” button.
If you have forgotten the list’s admin password, fill in the bug report form https://espiv.net/bug_report/