Can a Presidential executive order overrule a state or national constitution?

No. The President cannot do that

No.

The President's executive order is not law.

Per the tenth amendment, the federal government does not have a power unless the people give it that power. Here is the actual amendment

AMENDMENT X

"The powers not delegated to the United States by the Constitution, nor prohibited by it to the states, are reserved to the states respectively, or to the people."

Obama is sure in his own mind that he is our supreme leader and that he knows better than us what is good for us.

This is unfortunate.

I don't see much future for the Americans. It's a decayed country. And they have their racial problem, and the problem of social inequalities . . . Everything about the behavior of American society reveals that it's half Judaized, and the other half negrified. How can one expect a State like that to hold together - a country where everything is built on the dollar?

Adolf HitlerRemarks January 1942 recorded by Martin Bormann, published in Hitler's Table Talk (1953)

All of these questions and their answers depend on the mood the Supreme Court is in at the time. They can make the Constitution of the United States say whatever they want it to say.

executive orders can and do become subject to legal actions, with courts occasionally over ruling them when they overstep boundaries. AS a rule, they only affect federal agencies and have no direct affect on state or federal laws.