A software hacker, who go by the name HeathCliff, has released an excellent tool called “Windows Phone Internals” that allows Windows phone owners to unlock their smartphone’s bootloaders, gain root access and even create and run custom ROMs. The tool supports “most versions of Windows Phone 8.1 and Windows 10 Mobile” Microsoft as well as Nokia have made Windows Lumia smartphones difficult to break into at a low-level by locking down their boot loaders. HeathCliff is very well known XDA Developer and one of the Windows Phone legends.
Source: https://thehackernews.com/2015/11/root-windows-phone.html