Anyone is free to leave the United States whenever they wish. What they are not free to do, is to take parts of the country with them. Nor can they pass ordinances which strip loyal Americans of their US citizenship, which is what secession is. And yes, I call that treason.
So the “Union” is a farce. You do not believe in States rights. You do not believe in the United States at all.
Which Confederates were convicted of Treason?