Can the President kill whomever he wants so long as the target is monstrous and the public approves?

Osama has been on the FBI most wanted list for years. It was understood by everyone including pakistan that if he was found the US will take him down even if they had to kill him. No the president can't kill anyone he wants. The us constitution says that he may not kill another head of state. He also doesn't have judicial powers so he can't kill us citizens But Osama was the leader of a terrorist group that has killed 1000s of innocent people. I'm glad that devil is finally gone.