de-selected Use on Registration checkbox, but term still shows up on registration page

We have a user term that we created and initially wanted on the registration page. So on the User Terms administrative page we selected "Use on Registration". Everything worked fine.

We now do not want this term to show up on the user registration page, so we de-selected the checkbox for that term for "Use on Registration". We've cleared caches and done everything we can think to make sure the page isn't being cached in some way. But that term still shows up on the user registration page.

I see there there were previous tickets, now "fixed", that mentioned this problem.

Our user registration page is: http://deepcarbon.net/user/register