ill keep this short its really very very easy to do. you need to have an iso of the matching version to your previous os i.e. home or pro and x86 or x64. extract the iso (or you can mount it if you know how) go to \Windows\x64\sources and copy gatherosstate.exe to your desktop. run this file (may have to select run as admin) it will create the file GenuineTicket.xml on your desktop. SAVE THIS somewhere like a usb drive or otherwise YOU NEED IT LATER. now install windows 10 clean once done copy the file you saved GenuineTicket.xml to the folder C:\ProgramData\Microsoft\Windows\ClipSVC\GenuineTicket now reboot the machine. you should now be activated.