What you say may be true however in this situation you are obligated to kill one of the two.
You appear to be some kind of troll…

You don't need to shoot Hitler. Tell him you're from the future and he not only loses the war, but the Jews run the world. He will kill himself.
My password is password

This sounds like the type of question my kids used to ask.
Who do you like best? You're not allowed to say both and you have to answer.
It's definitely a trap but okay, baby Adolf gets the bullet.
You stupid fuckers, you know who you are.

Let's say yes for both.
As previously stated, "neither" is not an option.
A baby has to die.
You appear to be some kind of troll…

Is Hitler a baby in this scenario?
You stupid fuckers, you know who you are.

If someone has gone to the effort of providing you with a time machine and a gun it would be VERY rude not to carry out a simple request like this.
You appear to be some kind of troll…

Neither. What I would do is tell both of them I'm from the future and explain how their actions ultimately resulted in the destruction of everything they stood for.
My password is password

My password is password

No, different time period but otherwise very similar people.
You appear to be some kind of troll…

Is Edward one of the Kardashians?
~Yermie
My password is password

Hitler
“There are no atheists in foxholes, eh?”-Keith Jennings from the Omen.

No that would be too easy, the fun is derived from making a tough decision.
You appear to be some kind of troll…

You can’t assassinate both of them?
Fine, I’d choose Hitler.
“There are no atheists in foxholes, eh?”-Keith Jennings from the Omen.