The JCPOA wasn't a treaty and wasn't subject to Congressional approval, I'm not surprised you don't understand the Constitution. The Paris Accords were likewise an agreement not requiring ratification.
Meanwhile, the Treaty on Open Skies and NAFTA were both approved by Congress that Trump revoked, for no other reason than he's orange I'm guessing. His successor trade agreement funnily enough has all of the elements of NAFTA, but stuck a sunset provision on the whole damn thing since evidently he hates American businesses earning a profit.