I have done this myself and it works 100%. I understand there is a similar post but it still has some vagueness in it and I believe some individuals think you must only upgrade with the .exe, which leaves files behind (it left fraps behind even though I did a reset, etc). You can do a FULL clean install this way.
- Upgrade your Windows 7 or Windows 8.1 System to Windows 10.
- If you are having issues receiving your upgrade download this:http://www.microsoft.com/en-us/softw...load/windows10[1] and select "Upgrade this system", allow it to run and upgrade your system.
- Once you have upgraded make 110% sure you are on an Activated Windows 10 Operating System and verify the VERSION you have: Home, Pro, Etc. This can be done via System in Control Panel.
- Download this tool again on your Upgraded Windows 10 Installation:http://www.microsoft.com/en-us/softw...load/windows10[2] .
- Select Download for Another Computer. Select the appropriate version of Windows 10 and create an ISO.
- Install using the USB/DVD ISO you've created as you would a fresh installation of any Operating System.
- When prompted for a Product Key select skip. It will ask several times just continue to skip.
- When you are in your new Clean Install it will automatically activate when you are online.
This was taken from Microsofts site:
Note
If you upgraded to Windows 10 on this PC by taking advantage of the free upgrade offer and successfully activated Windows 10 on this PC in the past, you won't have a Windows 10 product key, and you can skip the product key page by selecting the Skip button. Your PC will activate online automatically so long as the same edition of Windows 10 was successfully activated on this PC by using the free Windows 10 upgrade offer.
http://windows.microsoft.com/en-us/w...d=ms_wol_win10[3]
EDIT: Some users are stating that Windows 10 is requiring several restarts before it activates or throws an error code. It should eventually activate. Remember that the servers are likely overloaded right now. In an effort to force the activation you may try this:
For all that get the message "Windows can't activate right now. Try again later" open an elevated command prompt and type "slmgr.vbs /ato" (without quotes).