Important for those that have already have Windows 10 Installed and may want to go back to Windows 7. I can't verify the following is true, since I haven't had time to check with Microsoft. However, it's worth finding out.
Scenario 4
If you simply do not want to have Windows 10 or it is not compatible with some of your hardware and software then just revert back to your previous operating system.
Be aware there is one caveat to this process and that is you must do it
within 30 days of upgrading to Windows 10 or the capability will be gone
because your old Windows installation related files will be
automatically removed from the upgraded system.
I hope the MVP's on this site are informing those that are or have installed Windows10 of this possible time limit.