You should be able to do it with Apple Configurator (search the app store - it is free) on a desktop or laptop mac, this suggestion assumes you are? (I am using version 2.3). The easiest way is if you can put the iPads in a charging cabinet with a USB connection to the mac (I have learned never to do more than about 15 at a time). Make sure they have enough charge or they will not show. If you don't have one you can try a USB hub connected directly to the mac, or do it a few at a time with USB cables. This is how I do it:
- In the app, once all are connected and showing, select them all in the list
- Choose 'profiles' (either using the 'Add' icon or menu bar 'Actions>add>profiles)
- Select the profile you want to remove and press the delete key (backspace)
It will take a short while but should remove it on all iPads highlighted unless there is some other restriction. I would advise trying one iPad first before doing them in bulk.