How do I unsubscribe from a geekpedia thread update?

Years ago I commented on a thread at geekpedia.com. At the bottom of the reply page, I checked the box for "Subscribe me to future replies". Now I get an email for every reply - and I no longer care about the thread. Lots of the replies are spam anyway. There is no login or account. I just typed a reply and provided my email address and checked that box. I've tried adding another comment with the same email address entered, and unchecking that box. That didn't work. How do I unsubscribe?