Windows 10: How do I revert back to an earlier Windows version

OEM systems that have been upgraded to Win 10 acquire a digital license which obviates the need for OEM disks or product keys.

Source https://support.microsoft.com/en-gb/...-10-activation
Activation helps verify that your copy of Windows is genuine and hasn’t been used on more devices than the Microsoft Software License Terms allow. Depending on how you got your copy of Windows 10, activation will use either a digital license or a 25-character product key.

Digital license (called a digital entitlement in Windows 10 Version 1511) is a method of activation in Windows 10 that doesn't require you to enter a product key.


How you got Windows 10
Activation method You upgraded to Windows 10 for free from an eligible device running a genuine copy of Windows 7 or Windows 8.1.
Digital license

 

I think Mark is talking about needing Windows 7 OEM install media. If you want to go back to the original Windows 7 OEM-SLP activation, then yes, you'll need the Dell OEM install media for that make and model. You wouldn't normally get that anywhere other than from Dell. You may find an ISO on bit torrent but I personally wouldn't trust it or touch it with a 10 foot pole. The other alternative is to use stock install media and the key on COA sticker. OEM-COA activation, assuming you can still read the code on the sticker.

 

I couldn't help notice that the very first concern in this thread is that Windows Live mail wasn't working right. I've experienced this myself and in particular with the new outlook.com. Windows Live is or will be EOL (end of Life) next month. Some email systems are already acting fussy and have dropped support.

This link --- support .microsoft .com/en-us/help/18614/windows-essentials without the spaces will take you to announcement.

I know this doesn't address going to 7 back but I thought the original poster should be aware.