I noticed that Windows 10 doesn't really honor these settings: Folder Options > General > 'Show recently used files in Quick access' and 'Show frequently used folders in Quick access'. They are removed from Explorer, but looks like Windows still collects all recently opened files as lnk files in %APPDATA%\Microsoft\Windows\Recent. There are also subdirs AutomaticDestinations and CustomDestinations, I guess these store the recent folders. I tried setting the group policy 'Do not keep history of recently opened documents' in Start Menu and Taskbar, but it had no effect. It's an old policy setting, but it worked in Windows 8. I guess this privacy feature was "lost" when coding the Quick Access feature in W10
When I run my backup script it contains a line: del %APPDATA%\Microsoft\Windows\Recent\*.lnk I've been doing that for a long time so that my hard drive and my backups don't get all cluttered up with that junk.
I solved this by setting it directly to registry: [HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\Explorer] "NoRecentDocsHistory"=dword:00000001 It doesn't work through policy editor, yet another bug in Windows 10 (Pro).