How did anyone "destroy a race"? Africa was a continent of slaves long before Europeans got there. Enslaving and killing each other was what Africans did. All that the white Europeans (and the many Muslim and Jewish middlemen) did was buy some of the merchandise that was up for sale.
The idea of abolishing slavery came from white western Europeans. Slavery was never just about the black race. That was an invention of the liberal race hustlers. They can never allow black people to move on from slavery. They must keep them enslaved to the government.