[HonkyTonkMan]

You can roll back from Win10 to Win7/8 within 30 days of the upgrade.

30 DAYS AFTER THE UPGRADE YOU CAN ROLL BACK.

Basically go to
1. Start -> Settings -> Update & Security -> Recovery.
2. Select "Go back to Windows 8.1", then "Get Started
3. You will be asked a couple of questions about rolling back, then it the restore begins.

The restore was fairly quick AND restored all data.

Tom's has a good write up w/ screenshots here: http://www.tomshardware.com/faq/id-2738057/uninstall-windows.html

[HonkyTonkMan]

/edit...”Up to 30 days after the upgrade you can roll back”

[JimRed]

Bookmark.