“So an executive order cannot be undone by the new executive?”
“Rules” passed by the EPA have the effect of laws. You can go to prison for violations. Congress surrendered its law making power to the EPA. Thus, the executive order was turned into a law, or so I’d argue if I were on their side. Also, this is as political as the lower court judges blocking the travel ban. I think it will be overturned. In the meantime, all the EPA has to do is let it be known they are suspending enforcement.
“...Congress surrendered its law making power to the EPA...”
Eliminate the EPA...