Well, things may have changed, but the way this used to work is that it can only be shut-off via your PayPal account and it can only be enabled during renewal.
So, if you log into PayPal, do a search for Subscriptions...you will likely need to adjust the dates so it will find your last BRS Membership purchase. Click on the 'details' link of the BRS membership record and you should be able to cancel or update the subscription from there.
If you do not have it set to auto-renew and would like to do so, simply renew and choose the option with the *...
I'm not aware of any other way to accomplish this but there may very well be other ways.