Hide full classes from sign up page

How do I hide full classes from the sign up page?  I've look everywhere and can't find an answer.

Basically when I send the link I want customers to only see classes that are available to schedule - not all the classes (included ones that are full and can't be scheduled). Basically hide the full classes (circled below).

I'd like to know an answer to this topic, too, but I'm not that skilled yet. I'd like to know how to hide classes/products from my page or list "unavailable" when they are closed.