Yes because according to the question I would have lived during the time of Hitler and did not travel back in time. Therefore, I wouldn't have to worry about paradoxes and changing a future that has yet to be written.
1890. Adolf Hitler is a baby. You're yourself, just happen to live in a different time. You're the only person on earth to know what Hitler will become in the future. Trying to explain this to other people would be pointless, as no one would believe you. A perfect occasion comes about and you can kill Hitler while being unnoticed. Would you do it? Note: The topic is about the act now or never. Options like I'd become Hitler's mentor are out of the discussion's scope.
No, I would not kill Hitler. It has nothing to do with whether I think I would be morally justified in killing someone who would later order the death of millions. I'm not a violent person. I'd be too nervous to get away with slipping poison in his food or drink, I would hesitate too long with a gun in my had and he'd probably take it away from me. A violent attack, like stabbing, strangling, etc. isn't really in me. Maybe I could kill someone in self-defense, but not as a premeditated act. If I'm just me as I am, but living in Hitler's time, that's what would stop me.
I'm not sure it would help anyway. Killing Hitler wouldn't change the rampant inflation and starvation that was occurring before Hitler took power. People were desperate for a leader who could fix things. Someone very much like him could have taken power instead of him. So even if I could bring myself to kill him, I'm not sure that it would be morally right to do so because the alternate outcome would be at best uncertain. The only sure way to prevent Nazi Germany, or something like it from happening, is to prevent the desperate circumstances that allowed Hitler to rise to power in the first place.
(This response has been edited in such a way that it has been rewritten entirely.)
Read more sci-fi. Killing a person may not possibly change the course of the history much; if the circumstances are so anyone can be a bloodthirsty dictator, possibly even worse than the one you're targeting. In this specific case I suggest you read on Stalin, you'd be surprised how much similarities you'll find. And that's just the 1930s.
ww2 is a heavy lesson of what we should not to do, but, there is no way, to change 1 thing in the history chain without changing the others. Just answer urself do u really want to kill this world just to make justice in time?
first thing that came to my mind is Hellboy. But then i can't and i shouldn't change history. So let it be. Its better to live with the pain of knowing what will happen than to live with the pain of guilt.