When copying and syncing images from Windows to iPhone in iTunes, a backup is created every time. This backup cannot be disabled, or seems troublesome to disable, so if you at least want to stop backing up to the C drive, you can change the backup destination folder.
Delete the Backup folder and create an _itunes folder.
Open cmd with administrator privileges and create a junction link with the mklink command.
In the example below, we’re changing the default backup destination folder “C:\Users\username\Apple\MobileSync\Backup” to an external HDD folder “N:_itunes”.
This effectively means that file operations directed to “C:\Users\username\Apple\MobileSync\Backup” will be performed in “N:_itunes”. (Backups are saved to “N:_itunes”)
# mklink /J "C:\Users\username\Apple\MobileSync\Backup" "N:\_itunes"
Junction created for C:\Users\username\Apple\MobileSync\Backup <<===>> N:\_itunes(Reference)