Need to remove iPad 4 from Configurator

I have an iPad that will not take a charge & will not power on. I've taken it to a local iMechanic who also could not get it to take a charge or power on. My problem now is that I need to remove it from Apple Configurator. Currently it is listed as checked out to a user & supervised. Any advice on how to get it "checked in" and remove it from my list of devices?