Normally in the past when you dont have carbonite installed, and you are in an instance such as Molten Core, and you've gotten to the end, you could right click an icon on the upper right, an eye i think it was and you had option to teleport out ....
...so the question is how to do this with carbonite?
That icon is attached, by default, to the minimap. I suspect that, like other icons that become attached to the minimap (for opening up various addons, for example) carbonite moves it, by default, to its "minimap button bag" or whatever carb calls it. That defaults to a list of icons down the right side of your screen. I'd look there.