To begin, login to Windows 8 and move all important files and folders to external storage device, remote network location, or to local drives except one on which Windows 8 is currently running. Once data backup is complete, reboot your system, choose Windows 7 from boot options.
After logging into Windows 7, open My Computer, right-click Windows 8 drive, and select Format. Select File system followed by default Allocation unit size, enable Quick Format and click Start to begin the disk formatting process.
After formatting the drive, you need to remove the Windows 8 Developer Consumer Preview boot option from Advanced Boot Options menu. This requires using BCDEdit command to modify or remove the Windows 8 Developer Consumer Preview boot entry. However, if you want a GUI alternative for BCDEdit command, download BOOTICE.
BOOTICE is a portable, Windows utility which allows you to edit Boot Configuration Data file from a simplified interface. Launch BOOTICE.EXE and head over to BCD Edit tab. Make sure that The System BCD option is enabled. Click View / Edit button.
It will open BCD editor. Select Windows Developer
Consumer Preview from left sidebar and hit Del to delete the Windows 8 Developer Consumer Preview entry from Advance Boot Options menu. You can follow same steps for removing Windows 8 Server Developer Consumer Preview from the system. After you’ve formatted the Windows 8 Server drive, launch BOOTICE, open BCD editor and delete the Windows Server Developer Consumer Preview entry in system BCD file. Users who did a clean install of Windows 8 Developer Consumer Build after removing Windows 7 need to use Windows 7 installation disc to remove Windows 8 Developer Consumer Build and then install Windows 7 on their PCs. As of now, Windows 8 doesn’t allow upgrading your PC from Window 7 to Windows 8. We will keep this post updated with Windows uninstallation methods for each iteration of Windows 8 version.