¿What do you do when the employee who protected the file left the company? ¿Or if you want to remove the current protection policy and apply a new one? The answer is Super User.
As an admin, you can configure, publish and update policies and labels, but you cannot override permissions. That task can only be performed by a Super User.
Super Users are not enabled by default, but you can do so by following a couple of simple steps:
That's it. The super suer is now able to override permissions on any protected file (handle with care!)
More information here.