Old operating systems

Hi All,

When I log in to My Norton the system reports that my Windows 10 device is proteced but that my Windows 8.1 device is not. However they are the same device, I upgraded from Windows 8.1 to Windows 10 some time ago. Is it safe for me to delete the 'windows 8.1 device' from the system as it doesn't really exist anymore? When I select delete the system warns that some protection may be lost, why is this?

Thanks,

Laura