Good evening Daniel and welcome to the Events Calendar Support forum!
Thank you for reaching out to us.
I would love to help you with this topic.
If I understand correctly, you are able to do all that you need, you just want to make sure nobody ever sees a specific category on the main calendar page.
The proper way to do this is with a bit of customization.
Either some code in the functions.php file of your WordPress theme or via a theme override (view customization).
You might want to read our Themer’s guide to get a sense of how that works.
Additionally, I believe this other thread could help you achieve what you are looking for: https://theeventscalendar.com/support/forums/topic/hide-category-from-main-calendar-but-not-category-calendar/
Let me know how that goes.
Best regards,
Geoff B.