I don't know how true this is but found this in the comment section at the link below.
Windows 10 installation program will give you three options before starting the upgrade:
- Install Windows 10 and preserve personal files, software and configuration.
- Install Windows 10 and preserve only personal files.
- Install Windows 10 without preserving anything. This is not a complete wipe though, as Windows still saves some stuff in C:\Windows.old in case something goes wrong during the installation. For a 100% fresh install one should download the official ISO from Microsoft Download Center (once it is available), put its contents on a DVD or a flash drive and boot from there. That way the installer will give you the option to wipe the...