https://winaero.com/blog/how-to-deactivate-windows-10-and-change-the-product-key/
slmgr /upk

slmgr -ipk your-new-product-key
VK7JG-NPHTM-C97JM-9MPGT-3V66T is generic win10 pro key
TX9XD-98N7V-6WMQ6-BX7FG-H8Q99 is generic win10 home key
HNJGQ-7Q26G-V6DB3-W8H3Q-63BQB is VLK 

slmgr.vbs -ipk VK7JG-NPHTM-C97JM-9MPGT-3V66T
slmgr.vbs -ipk HNJGQ-7Q26G-V6DB3-W8H3Q-63BQB

http://winsupersite.com/windows-10/what-are-windows-10-n-and-kn-editions

===================================================================
slmgr.vbs /dlv (Tells you what license you have)
slmgr.vbs /upk (Uninstalls current license)
slmgr.vbs -ipk HNJGQ-7Q26G-V6DB3-W8H3Q-63BQB (Installs VLK)
Should activate now after a bit
====================================================================

Default Product key that matches your Windows Edition

    Windows 10 Home Edition YTMG3-N6DKC-DKB77-7M9GH-8HVX7

    Windows 10 Home Edition Single Language BT79Q-G7N6G-PGBYW-4YWX6-6F4BT

    Windows 10 Pro Edition VK7JG-NPHTM-C97JM-9MPGT-3V66T

    Windows 10 Home N Edition 4CPRK-NM3K3-X6XXQ-RXX86-WXCHW

    Windows 10 Pro N Edition 2B87N-8KFHP-DKV6R-Y2C8J-PKCKT



    Try entering the generic product key for your edition:

    Home - TX9XD-98N7V-6WMQ6-BX7FG-H8Q99

    Pro - VK7JG-NPHTM-C97JM-9MPGT-3V66T

    Click Start, type: CMD

    Right click CMD

    Click Run as adminstrator

    At the command prompt, type the following commands:

    slmgr.vbs -ipk xxxx-xxxx-xxxx-xxxx (allows you to replace the current product key with the specified)

    xxxx-xxxx-xxxx-xxxx - represents your product key

    Hit Enter on your keyboard

    Exit the command prompt

    Restart your computer

    Give it a few days

slmgr.vbs -ipk VK7JG-NPHTM-C97JM-9MPGT-3V66T
slmgr.vbs -ipk HNJGQ-7Q26G-V6DB3-W8H3Q-63BQB

 Method One:
This method will work if you already have an activation key or KMSpico Key. 
You need to uninstall the existing key before applying the new one. 
Open command prompt in admin mode  and execute: (slmgr.vbs /dlv) without bracket before 
uninstalling the existing key.
You will find following description, note the description:

Description: Windows(R) Operating System, VOLUME_KMS_WS12_R2 channel

Next: Apply:  slmgr.vbs /upk to uninstall the existing KMS key:

slmgr.vbs /ipk <NewKMSProductKey>

Now go to PC Settings >Update and Security > Activation.

And you will find your windows 10 activated.