Windows 10 seems to be downloaded automatically if you reserve a free upgrade from Windows 7 or Windows 8.1 to Windows 10…
Upgrade to Windows 10 - Media Creation Tool
Download Windows 10 disc image (ISO file)
How to revert from Windows 10 to Windows 7/8.1 - Downgrade
Related articles for Windows 10
Book a Windows 10 Free UpgradeCheck if Windows 10 works on your computer - cancel the reservationUpgrade to Windows 10 - Media Creation ToolUpgrade from Windows 10 Home to ProClean install Windows 10Windows 10 settings and usage summary
