It was always possibly to dissolve the union through mutual consent of federal and state governments. It still is. It could be done by an act of Congress or a Constitutional Amendment. It can't be done by a state acting on its own. There is no right in the Constitution for a state or locality to break with the Constitution and declare itself independent and free from federal laws.
The Declaration of Independence was written and signed when war had been going on between the colonies and Britain for over a year. It asserts a right to revolt and a right to independence, but says that "Governments long established should not be changed for light and transient causes." In other words, it doesn't say that you can throw over membership in a nation whenever you feel like it.
The Declaration of Independence says there is such a right, and it stems from God and Natural law. In their understanding, this overrides anything written by man. The right is inherent in human nature, and we recognize it's application in nations like Ukraine despite Putin's efforts to "preserve the Union." (Soviet Union.)
... but says that "Governments long established should not be changed for light and transient causes." In other words, it doesn't say that you can throw over membership in a nation whenever you feel like it.
Phrased as a suggestion, not as a requirement. Don't put it forth as a requirement because that is deceptive.