The cockroach has a reputation for being impossible to kill, but that in itself is not exactly true. Instead, there is one way that is going to work for them, but it is not going to be fast in any way at all.
Now, while you may initially think that cutting off its head would do the job, then you might want to know that the brain of the cockroach is in its body, so it will keep on living for several weeks even without their head. However, they would eventually die as a result of this wound, but not for the reason that you would expect.
It turns out that the cockroach would starve to death rather than it being killed due to it being decapitated. Yes, while the chopping of the head does not work, it all boils down to them being unable to eat just like any other insect or animal out there.