Choose "Custom: Install Windows only (advanced)" if you want a clean installation. This allows you to delete old partitions and start fresh.
Follow the on-screen instructions. Select your language, time, and keyboard preferences. download windows 8.1 disc image -iso file- - microsoft
Use the Windows 7 USB/DVD Download Tool (which works for Windows 8.1) or a third-party tool like Rufus. Choose "Custom: Install Windows only (advanced)" if you