Windows 10: Roll back to previus Windows version and product key

I have a Lenovo laptop with Windows 10 Home Edition preinstalled. When I entered Uni, they provided us an Educational license which I switched to. However now that my college is completed, many of the features are blocked/cannot be changed as they are still 'managed by my organization'.How can I revert back to my preinstalled version of Windows? I managed to get the OEM product key but the 'change product key' function says 'The product key does not work'.

:)

 

previus build

hello i have installed win10 build 1709.but many programs don't work properly.i can't go back to previus version because i make a clean installation and isn't available anymore.can i download manually a previus version,and
where can i find it?also how can i contact with official microsoft support for this issue?

 

Windows Product Key

A friend of mine has an all-in-one that came with Windows 8 pre-installed. He erased the original OS thinking he could install another version of Windows 8. One thing he encountered, that he didn't expect, the BIOS/UEFI has a password. So, basically he is locked out from installing another OS. His BIOS has the product key nestled inside. Is it possible to find out which version the product key belong to?

 

New Version of Windows XP to Combat Lack of Product Keys

The current version of Windows XP Service Pack 2.0b is currently running very low on product keys, due to piracy the surprising longevity of the product. And so, to combat the lack of product keys, Microsoft is creating a fresh batch by releasing Windows XP Service Pack 2.0c. There should be no major differences, other than the latest patches built in and the new abundance of keys.

This version of XP will only be available to OEM system builders, and will only be in the market until Windows XP's official EoL date: January 31st 2009. Retail copies of Windows XP will stop shipping on the January 31st 2008.

Source: Technet