Well, of course, he can. Right wingers will tell you differently, but they're lying.. They'll tell you that he has to get APPROVAL from some bureaucrat, and then get APPROVAL from his generals... That's LAUGHABLE on its face, when you consider that he has ONLY 9 minutes to decide whether to shoot or not. CLEARLY, there's NO time to consult with ANYBODY.. I say that, because the assumption under which the president would FIRE his nukes, is that the ENEMY has already FIRED theirs and they're on the way.
His handlers took his Twitter account away from him during the last days of the campaign, because they KNEW he couldn't be trusted. Now, NOBODY, but NOBODY can take away his nuclear bombs..