It wasn't put like this in the communist manifesto but it was expressed many times in their writings.
They understood that if you magically transferred the wealth from the rich to the poor, the rich would get it all back within a few years.....so eliminating them permanently was the only way to solve that problem.......The Bolsheviks understood this as well during "The Red Terror":
"Do not look in the file of incriminating evidence to see whether or not the accused rose up against the Soviets with arms or words. Ask him instead to which class he belongs, what is his background, his education, his profession. These are the questions that will determine the fate of the accused. That is the meaning and essence of the Red Terror."
- Martin Latsis, chief of the Ukrainian Cheka