The law giving CA the right to make its own standards was passed by Congress and signed by a president. That means the president just can't wave his hand and declare he gets to revoke the law because he doesn't like it. To change that law, Congress would have to pass another law.
Is it that you don't understand this, or is it that you adore the thought of dictatorship so much, you don't care about Constitution-rape?
But then, you are a libertarian, so it's a given that you lust for a daddy-figure to be a supposedly benevolent dictator. Libertarians think that democracy gets in the way of freedom, and they define freedom as "whatever makes me money."
Deniers in general, being authoritarian followers at their core, don't even care about the benevolent part. They just want a dictator, end of story, to get even with all the liberals who humiliated them all of their lives.
Liberals, of course, are for liberty and the Constitution, so they don't support the president-as-dictator thing.