Disabling the Allies window

The gameplay in my map involves quite a bit of deception, color-changing, and name-changing, and I need to keep players from being able to click the Allies button in order to get a full list of what everyone's names and colors are.

So, how do I disable that button? I looked around in the Gameplay Interface window and fiddled with a couple things, but nothing quite seemed to affect it. What should I do?