MDM stands for mobile device management. It’s a corporate IT’s way of remotely managing the machine like locking it down from being used or allowing drastic changes to the OS. Depending on the one being used (like Intune from Microsoft), it could be tricky to get around it.
But with most, you can get around it by wiping the OS and starting fresh or getting a new hard drive (if possible).
They are generally dependent on the OS that was installed, but I’m sure one could exist on the hardware level that makes this difficult to bypass by just swapping the OS or hard drive.