you mustn't sell the computer with an operating system (or any other software) installed, unless you also pass on the necessary CD and licence sticker/documents/registration keys.
If you don't have those you should format the drive.
Samsung Galaxy S8 review
1995-2015: How technology has changed the world in 20 years
This poetic animation about monsters is illustrated in a Van Gogh painterly style
Apple predictions 2017
Synology invites you to visit them at Insomnia on 26th – 29th August. Book your tickets now and visit Synology.