Good evening Justin and welcome to the Events Calendar Support forum!
Thank you for reaching out to us.
We are sorry to hear about the snippets not working out for you.
I would love to help you with this topic.
Actually, the snippets are not meant to go in your custom CSS section. Instead, you can apply them in the functions.php file of your theme (without the PHP tag at the top).
That being said, if you are looking for a CSS solution.
Try adding the following CSS rule to your style.css file or in your Custom CSS metabox:
.tribe-events-ical {display: none !important}
Let me know how that goes.
Best regards,
Geoff B.