Is USC in-person or, like many universities, are they saying that to make sure the cash keeps coming

I would suggest emailing - that is how the person who posted on the USC Parents FB group got replies. She posted the form on the FB page and it looked like you had to cancel for whole year - though there was also an option to cancel for Spring 2021 but I imagine that would only be if it was already later than Fall or your contract didn’t start til Spring.