Downgrade from Windows 10 Pro to Home

Unfortunately, clean install is your only option, you can’t downgrade from Pro to Home. Changing the key will not work. You could try the following work around then test your luck:

1. Open Registry Editor (WIN + R, type regedit, hit Enter).
2. Browse to key HKEY_Local Machine > Software > Microsoft > Windows NT > CurrentVersion.
3. Change EditionID to Home (double click EditionID, change value, click OK). In your case it should at the moment show Pro.
4. Change ProductName to Windows 10 Home. In your case it should at the moment show Windows 10 Professional.
5. Browse to key HKEY_Local Machine > Software > Wow6432Node > Microsoft > Windows NT > CurrentVersion, change the same two values as in steps 3 and 4 above.
6. Close the Registry Editor.
7. Insert the Windows 10 Home installation media, do an in-place upgrade by launching the setup from desktop (not booting with Windows 10 Home install media).
8. When asked, enter your valid Windows 10 Home product key and select what to keep (settings, personal files and apps, only personal files or nothing).
9. Windows 10 Home in-place upgrade will be done now.