Un-installing Windows 10 from automatic install
Here is the steps to un-install the Windows 10 from the automatic upgrade
Step 1 : Open Control Panel
Step 2 : Select Settings. The following Settings screen will display.
Step 3 : Select Recovery Option. Two Options will display. First 1 is "Reset this PC". 2nd options will display either "Go Back to Windows 8.8" or "Advanced Setup" . It is based on the days completed after the automatic installation.
Step 6 : Select Go Back to Windows 8.1 if it is available. It will start un-installing Windows 10 and reverting to Windows 8.1.If the option is not existing then recovery is not possible. You have crossed the no of days Limit.