Hi Alex,
Normally file sync maintains identical copies of your Creative Cloud Files folder, one locally on your computer and one online in your Creative Cloud file storage. It is possible to only have copies on the cloud, and delete the local copies, but that wasn't really the way it was intended to be used. To do that you would want to turn off file sync from the Creative Cloud app preferences. I'd just caution you to make sure anything you delete locally has already been uploaded to the cloud before deleting. You can work through a browser to upload and download files with file sync turned off. Adobe Creative Cloud
You can turn file sync off here

Cheers,
- Dave