[Non-Sequitur]

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.

The power to approve a change in the status of a state is an power delegated to Congress, and by implication that would include leaving altogether. The power to act in a unilateral manner where the interests of other states are impacted is a power explicitly denied to the states in a number of ways. By implication that should include the ultimate impact, secession.

[Leatherneck_MT]

Do you mind enumerating those powers within the Document itself?

I'd like to see them.