How to keep your local account while linking a Windows 10 license to a Microsoft account

[WindowsCentral.com]

Windows 10 allows you to link your product key to a Microsoft account to re-activate the operating system, here's how to do that and still keep your local account.

With Windows 10, linking your product key to your Microsoft account so you can easily re-activate the operating system when you make significant changes to the hardware on your PC, such as replacing the motherboard, processor, or hard drive.
You can associate your operating system license with a Microsoft account, but in doing that you'll be required to switch to a Microsoft account. If you want to tie your license to a Microsoft Account but keep using a local account on your PC, we can do that.

Full story from the WindowsCentral blog...