DBAN might be excessive, a Clean install as suggested below includes wiping drive anyway.
Go to settings/update & security/activation
If next to activation it says
Windows is activated with a digital license then your licence is currently linked to your motherboard.
Windows is activated with a digital license linked to your Microsoft account. then your licence is linked to a Email address you either use to login or gave to Microsoft when you upgraded from previous version of Windows.
Both of these are fine for a fresh install, you just may need to use the email address/password to create user if the current licence is linked to an Microsoft Account.
download the
Windows 10 media creation tool and use it to make a win 10 installer on USB
change boot order in BIOS so USB is first, hdd second
boot from installer
follow this guide:
http://www.tenforums.com/tutorials/1950-windows-10-clean-install.html
when you reach the screen asking for licence, click "I don't have a key" and win 10 will continue to install and reactivate once finished