How to perform a clean installation of Windows
You can perform a clean installation of Windows 8.1 or Windows 8 using installation media, such as a DVD or USB flash drive. You don't need a previous version of Windows installed on your PC to perform a clean installation of Windows 8.1, but you do for Windows 8. If your PC doesn't have a version of Windows already installed, you'll need install a previous version of Windows or buy Windows 8.1 or a System Builder version of Windows 8 at a local retailer if it's available in your country or region.
To perform a clean installation using a DVD or USB flash drive
If you bought Windows 8.1 or Windows 8 on DVD from a participating retailer, or created a DVD or bootable USB flash drive when you downloaded Windows using Upgrade Assistant, follow these steps to perform a clean installation.