NoFileAssociate, Always use selected program inactive

To disable file association add to registry:

reg add "HKCU\Software\Microsoft\Windows\CurrentVersion\policies\Explorer" /v NoFileAssociate /t REG_DWORD /d 1 /f

To enable file association add to registry:

reg add "HKCU\Software\Microsoft\Windows\CurrentVersion\policies\Explorer" /v NoFileAssociate /t REG_DWORD /d 0 /f

To set windows default state you can delete this key:

reg delete "HKCU\Software\Microsoft\Windows\CurrentVersion\policies\Explorer" /v NoFileAssociate /f