In direct opposition to warnings from MS and Forum Admins, many users have installed Windows 10 Preview, right over the top of their everyday (Main) OS, and the die is cast. Either they will have to stay with Windows 10, or RE-Install their original OS, providing they have it on an install disk.
The same thing happened when we were testing Windows 8. Every day someone would come on the forum asking "How can I get my Windows 7 back?" Microsoft had already told them, that there is NO return policy.
But I've been doing this stuff for enough years, to know that I will never put anything on top of my working OS, without a pre-determined exit strategy. I've been offered Windows 10 for free, when it's released on July 29.
But before I install that upgrade, I'll have my existing OS (Windows 8.1 Pro) cloned to another 1TB hard drive, so if the upgrade goes bad, or I just don't like it, I can go right back to Windows 8.1 like as if nothing ever happened.
Happiness is knowing that you can easily get out of a bad situation. Eh?
Cheers Mates!
TechnoMage