Managed Laptops

If you have a device that's been wiped and you're sure the wipe operation did not fail; however, you can still see previous client data on the machine, there's a high possibility that the device is enrolled in a device management platform (Example; Apple calls this "MDM").

 

An MDM is a cloud based application that allows admins to enroll devices into a company's domain system and automatically push out updates and company software to that device, whenever that device reaches out to the internet. Due to the way MDM works, the only way to remove this from computers and mobile devices, is to reach out to the previous owners and ask them to remove it from their management provider.