I recently decided that I really am not making good use of my SmugMug site, and I think that Adobe Portfolio will be good enough for me.
However, I'd just paid for another year's subscription, so what I wanted to do was to cancel the recurring direct debit. In fact, I ended up cancelling the account, with the result that everything disappeared, including my login.
Fortunately, SmugMug were able to reactivate my account, and I don't think that I lost anything, though with the caveat that they had recovered "everything the system allows".
Anyway, it turns out that you can't do what I wanted - you can't cancel the recurring payment. All you can do is to cancel the account, as I inadvertently did.
Obviously, my mistake, but to be forewarned is to be forearmed.
So be careful!
Dave