Its called Windows 7 Downgrader. Windows 7 Downgrader will let downgrade popular editions such as Windows 7 Ultimate, Enterprise, Professional quickly and easily. Once it downgrades, all you need to do is insert the Windows 7 installation and do a repair upgrade to a desired edition.

How do I downgrade from Windows 7 Ultimate to Professional without CD?

5 Answers. You cannot downgrade to Windows 7 Pro without doing a complete re-installation, and you cannot use a Windows 7 Pro activation key to activate Windows 7 Ultimate. However, you should be able to use the activation key from an OEM copy of Windows Ultimate that you purchase.

How do I downgrade from Windows 7 Ultimate to Home Premium?

Please note that one cannot perform a “downgrade” from Windows 7 Ultimate to Windows 7 Home Premium. You would have to perform a “clean install” of Windows 7 Home Premium using your original Windows 7 Home Premium DVD or your computer manufacturer’s recommended Windows 7 Home Premium recovery/reinstallation method.