Can Iron Man kill Thanos in Avengers 4?
The answer to the question "Can" is dubious.
Depends on a lot of factors, because Iron man is Marvel's main toy and Robert is completing his term as iron man.
So, adding all this he possibly can kill Thanos.
But would it be the way we would see it??
That's uncertain as of now.
Maybe all the heroes would fight him together and then iron man would be the one to land the lasting blow to kill him.
These would be one of the many ways Stark could kill him.
But if you're asking me that, could Iron man kill Thanos in a one-on-one fight??
Thanos is really powerful and is a better one on one fighter.
Iron man could use the bleeding edge but Thanos is a superior fighter with better intellect, skills and is highly durable.
All that Stark could do, was to make him bleed a drop of blood with all the shots from the bleeding edge armor.
That tells a lot about Thanos.
So, Stark alone even with the bleeding edge cannot beat The Mad Titan.
He's too strong, didn't you see how badly Hulk was beaten down unconscious by him so easily.
This is a feat Stark could not achieve with his Hulk buster with added parts.
Thanos did it in a few seconds.
So, it's hard for him to do it alone.
But with the Avengers on his side and everyone attacking him, he could kill him.