I would never sell a PC with a copy of Windows 10 that is licensed to me. Wipe the drive as per this web page and you should be fine. The new owner can then purchase a copy of Windows 10 for their own use.
Hello, I like to sell my Dell XPS 8700.  What can do to wipe the personal data clean from he PC?  There is Windows 10 on it.  Do I give the person buying the PC with Windows on it?  I see there is a option in Windows to reset windows and remove personal files.  Should I reformat the HD?  Thanks, Paul  
How to prepare Dell XPS 8700 PC to be sold?