I just got the Note 10 and actually had the same issue. What I did was to select to show only the phone contacts. I then selected all contacts and when I clicked delete I unchecked the option to Delete contacts from all linked accounts. That kept all my google contacts as is and only removed the ones saved to the phone. I would definitely backup google contacts first just in case.
That didn't work for me. I now dont have Samsung sync nor backup my contacts . This way there will be nothing appearing under contacts for device memory when one restores next time.