Of course there isn't any elites within a true Communist system (whether a truly pure Communist system is possible is another debate). We're talking theory not practice here...
As for those killed in the purges of the USSR, well to make an omelette you have to break a few eggs . Purges will be a part of any revolution, you can't expect the ruling classes to hand over the means of production to the dictatorship of the proletariat without bloodshed...
So to kill for the good of communism is no problem, but the Nazis were in the wrong, that's so f****d up i don't know what to say?