On the morality of killing Ubermensch

If it is true that Neitzsche said that an Uberman can do what ever he wants, even kill who ever he wants,

Then my QUESTION is:
A: can a lesser being, an Untermensch, an inferior, morally kill the Uberman ?
B: Would it be moral for group of lesser men, inferiors, band together and kill the Uberman ?
Why -- or why not ?
Thank you.