Just downloaded windows 10

This is what I found http://www.pcadvisor.co.uk/how-to/windows/how-downgrade-windows-10-to-windows-7-8-easy-3615606/

I just looked in my settings like shown in post # 29 and there is a section to revert back to what ever OS you had

Well someone screwed up somewhere then, as it can't be MS that will let you fix a screwed up upgrade.
OH!, it probably doesn't actually work. :D
That's how it's usually done.

Seriously though, I have only had a small amount of time with 10 so far, so I'm sure there are some things to explore.
By the time I got through the settings that share your entire life with the world I didn't have much more patience for it at the time.