Ability to hide certain subcategories from New Ticket view

Some of our users are getting confused on the differences between Service Requests and Tickets (New Ticket). Is there a way to hide certain subcategories from the New Ticket screen, and only have them visible in the Service Catalog?

I saw a similar feature request, it looks like it's a thing, however I'm having trouble locating/ figuring out how to do so.

Thanks!