Important: Before proceeding, copy the files in those special folders to another folder or external drive. Please don’t copy them anywhere under Desktop/Documents/Pictures. This is because disabling OneDrive backup for a folder erases the local copies of the files. Copying them to a different location beforehand will ensure that you don’t need to download them again from the OneDrive cloud.
Right-click the OneDrive icon in the Notification area and click Settings.
Select the Backup tab, and click Manage Backup
In the Manage folder backup dialog, click on the Stop backup link for "Desktop"
Click Stop backup in the confirmation dialog that appears.