You don't provide the URL for a Nabble archive so I am not sure you are talking about a Nabble archive or the mailing list itself.
On Nabble archives you can unsubscribe by clicking the appropriate button on the page that is normally linked from the header area of the archive page. However, it is also possible you are receiving the mail direct from the list itself. What is the "From:" address of the mail you are getting?
Volunteer Helper - but recommending that users move off the platform!
Once the admin for GregHelp now deleted.