This video displays the easy way of permanently removing the windows activation watermark "Activate Windows, Go to Settings to Activate Windows Watermark on Windows 10".
Not promoting the inactivated use of the windows for sure, but if due to any reasons you don't have the valid license for windows activation then this is helpful for you guys.
Let me know whether it works in your case or not . If it works then make sure to let others know as well which will be very much helpful I guess!