Unless there's anything which might get you into trouble with the authorities if found on 'your' machine, as you bought the machine on the understanding that it was a returned item I would just delete everything & forget about it.
OnePlus 5T review: Hands-on
Illustrator Andrés Lozano on his improv line work, brazen use of colours & hand sketching
iPhone X review
Comment envoyer gratuitement des gros fichiers ?