I bought a laptop from MM on 03.03.20, new!
Yesterday I accidentally discovered photos in the Photos folder and lots of them, at least 100 private photos!
So what should I do? I have apparently not got a new device, the previous owner will not be happy if he learns that his private photos and data are on my computer?!
Delete the photos and good.
You paid for a new device and got a used one. Take a look e.g. With CrystalDiskInfo how many hours it has already run. If that seems like a lot to you, complain to MediaMarkt.
You have not received a new device, so you can complain to MM, return it, etc.
If you do not want this, you can set up a new PC or simply delete the pictures, it is entirely up to you