Updating to a higher edition of Windows 7 is easy. But how to reverse it, i.e. demoting an Integrale (Ultimate) edition to Family (Home Premium), for example? This tutorial gives you a method that worked for me. To be implemented with caution, therefore!
N.B. : this method worked perfectly in my case: it won't necessarily be the same for you. I share this tutorial on an experimental basis only.
Step #1 — Download Windows 7 Downgrader
Most manipulations indicate that you need to modify keys in the registry to allow you to switch from an Integral (or Enterprise) edition to a Professional or Home Premium edition.
In the method I've experienced, just download the Windows 7 Downgrader utility:
Once uncompressed in the folder of your choice, run the only file in the archive.
Step 2 — Choice of Windows 7 edition to which to demote
The utility then displays a window. Simply click on the edition you want to switch to, either Downgrade to Home Premium in our case.
Step 3 — “Down Upgrade” of Windows 7
This does, insert the installation disk of Windows 7 — or download the ISOs corresponding to your edition, and choose Upgrade during installation.
Contrary to what is displayed on the screen, the system does downgrader. Normal, since you're already at the maximum level.
To perform the reverse operation, follow our Windows 7 Express Upgrade Tutorial.
Wait for long minutes: in the end, you should find all the programs and other documents belonging to you under the Family Edition as if nothing weren't. Don't forget to activate Windows with a new serial key corresponding to the right product!