The fact is that scuttling a spaceship would be trivial for its crew, the hard part of space is keeping the constant threat of death at bay. You don't need a button, any more than you would on a submarine, you just need an order given to a trained crew that knows their vessel. For things like secret information, use the same systems they do in embassies, which again boils down to an order given to people who know what to do.
