Is it true that blacks were created to stoke the flames of Gehinom? If so, and all blacks are doomed anyway and have no portion in this world or the world to come, is it a problem if a black is killed or chooses to no longer exist?
I have never heard of such a thing, and until I see something like this written, I take it as utter nonsense.
The Rambam writes that all human beings have freedom of choice and if they act correctly in this world they will benefit from their reward in the world to come. This includes blacks, and all other humans. As a side point Eliezer the slave of Avrohom was black, and he reached a very high spiritual level.