Sync option is new feature in SharePoint Online which sync content from document library to your local machine. It sync the content by using OneDrive client but data does not sync in OneDrive. It creates a separate folder.
You can control sync by enabling or disabling it. Below are the methods which can help you to control the sync option.
Disable sync from a document library:
Sometimes you don’t want to allow people to sync document library content on their local desktop. In order to hide the sync button you can uncheck the ‘download the offline connectivity’
- Go the document library settings and click on Library Settings
- Click on Advanced Setting
- Scroll down and check “Offline Client Availability”
- select “Allow items from this document library to be downloaded to offline clients” to “No“
Disable sync from Site Setting
You can remove sync button from the entire SharePoint site by disabling it from the site settings.
- Go to the site settings
- Under Search section select “Search and offline availability“
- under Offline Client Availability select “Allow items from the site to be downloaded to offline clients?” to No