It doesn’t have to be in the Constitution to be a right. There are 18 enumerated rights reserved for the federal government that it can override any state rights on that are related to the 18 enumerated powers.
Any powers not enumerated to the federal government belongs to the state. The Federal government has 18 enumerated rights and all other rights belongs to the state via the Tenth Amendment. Since not one of the enumerated powers of the federal government covers preventings states from leaving, a state has the right to leave.
The only thing the federal government can do, if a territory applies to join the Union, is that they can place conditions upon states entering. They can’t stop a state from leaving.
Trump loves Andrew Jackson, Jackson disagreed, both are NATIONALISTS.