Published on Nov 6, 2015 https://www.youtube.com/watch?v=r5GnFru0zas
Guide to downgrade Windows 10 Enterprise to Professional:
1. Open regedit.exe and navigate to HKLM\Software\Microsoft\Windows NT\CurrentVersion
2. Change ProductName to Windows 10 Professional
3. Change EditionID to Professional
4. Navigate now to HKLM\Software\Wow6432Node\Microsoft\Windows NT\CurrentVersion
5. Change ProductName to Windows 10 Professional
6. Change EditionID to Professional
7. Close regedit.exe (no need to restart)
8. Start the Windows 10 Pro installation from your installation media.