The Weimar Republic executes the entire leadership of the NSDAP after the failed Beer Hall Putsch in 1923.
Or Hitler could be killed by the bullet that OTL killed the marcher next to him.
(But that's actually adding an event, not removing one as the OP requested.)
That would eliminate Nazi Germany and its crimes.
But it does not eliminate the USSR and its crimes, nor its threat to the world as a nuclear power. I would be very reluctant to tweak history in the WW II-Cold War era unless I could be sure that no criminal government would have the Bomb. Not Nazi Germany, not the USSR, not Mao's China, not Imperialist Japan. Not even Fascist Italy.
Because once such a regime has the Bomb, it can do whatever crimes and aggressions it wants to, unless some lawful government has the Bomb to deter. Then comes a Cold War with a "balance of terror" and several decades when recklessness or accident could trigger the end of civilization.
We dodged that bullet OTL. But I would not take any chance of that outcome, not even to avert the Holocaust or the Holodomor or the Great Leap Forward. It's the gambler's fundamental rule: never bet what you cannot afford to lose, no matter how favorable the odds.
In this case: one eliminates the Nazis and their particular crimes, and most likely Germany as a military threat. But the uranium fission chain reaction is still going to be discovered, and therefore the Bomb.
The criminal regime of the USSR still exists, and Japan will almost certainly still go mad. Each of them is IMO more likely to develop the Bomb than any Western state not facing the very visible threat of Nazi Germany. (And serious Western development work started only after Nazi Germany attacked.)
Thus there is danger of Stalin having the Bomb to himself, or of Imperialist Japan having the Bomb. Either outcome would be much worse than OTL.
The West (especially the U.S.) was galvanized into strong military build-up and action by Nazi Germany, more than anything else, and the U.S. became a superpower with de facto global hegemony through its participation in WW II. No Nazi Germany, and the U.S. remains isolationist - and not an effective counter to the USSR, which would be much stronger for not having been ravaged by German invasion. And the U.S. would be much less likely to spend the vast amounts required to build the Bomb.
Even if the U.S. does stand against the USSR (or nuclear Japan), then there will be a Cold War with build-up of nuclear arsenals, and decades of risk of a nuclear-war catastrophe.
So this is not necessarily a good choice.