With the introduction of new Windows 10 S operating system, Microsoft also announced that anyone who wants to upgrade to Windows 10 Pro will be able to do that and for free until December 31, 2017. After then, they will be required to pay $49.
The software giant has now confirmed that Surface Laptop owners that want to go back to the original operating system will now be able to do that. The reason behind that is because Windows 10 S is more power efficient than Windows 10 Pro, meaning the latter will likely drain your battery faster.
To do that, use the official recovery image for the Surface Laptop. The only problem is it'll remove all your files.