Is there even a democratic mechanism for allowing this? The Feds back in 1861 didn’t think so.
Some folks argue that the 10th Amendment would allow it: "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."
But of course no federal bureaucrat or judge would agree.
So the only way to do it democratically would be by a new amendment to the Constitution, one that would allow citizens of a state to vote on the issue.
Good luck getting that one passed.
And it all goes back to this. The US government is strongly for letting folks everywhere else in the world vote on independence. But it ain't happening here. That's ironic, to the point of being hypocritical.
The democratic mechanism is what the states did in ‘61, which is to have the legislatures vote to secede. The feds back then wouldn’t let it happen, as they were both lacking in vision and radical, greedy, bloodthirsty, uncompromising, and just plain mean. Nowadays they’re the same, except stupider, simultaneously less self-aware and more self-involved, and there are more of them.