How do you unsubscribe an alias?

I have a placekeeper domain (let's call it NOSPAM.ORG) that forwards all mail, including PMAIL LISTSERV

I subscribed as pegasus_user@nospam.org

I can't send email as pegasus_user@nospam.org, gmail and my ISP send mail as
REPLY TO: pegasus_user@nospam.org
ON BEHALF OF: pegasus_user@nospam.org

but the sender is my gmail or ISP account

About once a year I try to unsubscribe when I see how much mail is in my junk folder

If you subscribed as pegasus_user@nospam.org but can't send email from that address then I think your only option is to login to the LISTSERV web page and manage your subscription there. Use the "Subscriptions" link in the left pane.
This is the URL to the LISTSERV page.: https://listserv.ua.edu/

Sadly the link asks me to log in, and offers no password recovery

https://listserv.ua.edu/cgi-bin/wa?RESET-COOKIE

That is the link it gives me to reset password if forgotten.

Wierd. My login screen contains a "Forgot Password?" link.

to clarify , I wasn't able to get a password for the email address that is subscribed. I opened a new account here for the address mike@mattos.ca and the new password works

But I still can't UNSUBSCRIBE

Ah, unsubscribe was part of an unlabelled pull down menu! Strange but seems to be done now

Thank you for your patience