Hi ​@Chip Ge, 

Welcome to Box Community and we’d love to further assist! 

For the folders currently marked as available offline, you can right-click on the folder and select “Make Available Online Only” from the context menu to revert it back to online-only status.

This action applies at the folder level; individual files inherit the status of their containing folder.

So, you cannot make a single file explicitly “available online only” independently—files follow the availability status of their parent folder.

Hope it answers your question, and let us know if you have questions or clarifications!