How can I Create a Registrable that isn't on the app?

Whether it is a class, event, or series, you have the ability to hide them from your displayed live schedule for clients on the mobile application. 

When creating classes, events, and series the final step allows for the options "Display on App" and "Publish Now." If you uncheck "Display on App" then the registrable is technically "hidden" from your client base. As a result it will not show on the mobile app, app online, or any widgets. Thus, the only way for clients to access the registrable would be with a share link.