The logo is just semi transparent plastic. The backlight lights up, the logo lights up. Turn your screen brightness off and you will see the logo is also 'off'. So, to 'shut it off' you'd have to get in there and cover the insides with something 100% opaque, so that no light can bleed through. The change the color you'd have to open it up and cover the inside with a filter so only one color of light gets through.
Or you could just spraypaint the back of your case krylon flat black if you want something 'different'.