You can not remove it without destroying it.
Best thing you can do if you really absolutely need to get it off, is to order a replacement band from Festool. It is a bit different from the one that's factory fitted. The original is clamped with a special tool, the replacement comes with a screw you can tighten yourself.
But the housing of the ETS is not something you just want to open on a whim. I've done it a couple of times with sanders that were really broken. It is not that easy to get them back together again.