I contacted support to check if this had changed and not only did they confirm that there is no way to cancel online, I was told that this is actually for my benefit! This was conveyed with a lot of corporate-speak trying rationalize the decision (or just confuse me).
An organization being greedy is one thing, but I really don't appreciate being gaslit about it. It's too bad because I like their work, but I won't support these kinds of business practices.