As principals, they came together in 1776 as "united States" or "United Colonies" according to the Declaration Of Independence.
As principals, in 1781, they created a general government as their agent through the "Articles of Confederation and perpetual Union..." (emphasis added).
As principals, in 1787, they created a federal government as their agent through the Constitution of the United States, in part to form a more perfect Union.
As principals they have the right to fire agents if they so agree, as they did in 1787, but that does not mean they have the right to unilaterally withdraw from the pact they have with each other, unless perhaps it's the right associated with "might".
Note:
From the "Articles of Confederation and perpetual Union...":
Article VI, second paragraph:
"No two or more States shall enter into any treaty, confederation or alliance whatever between them, without the consent of the United States in Congress assembled, specifying accurately the purposes for which the same is to be entered into, and how long it shall continue." (Emphasis added.)
Article XIII, first and second paragraphs (Emphasis added):
"Every State shall abide by the determination of the United States in Congress assembled, on all questions which by this confederation are submitted to them. And the Articles of this Confederation shall be inviolably observed by every State, and the Union shall be perpetual; nor shall any alteration at any time hereafter be made in any of them; unless such alteration be agreed to in a Congress of the United States, and be afterwards confirmed by the legislatures of every State.
And Whereas it hath pleased the Great Governor of the World to incline the hearts of the legislatures we respectively represent in Congress, to approve of, and to authorize us to ratify the said Articles of Confederation and perpetual Union. Know Ye that we the undersigned delegates, by virtue of the power and authority to us given for that purpose, do by these presents, in the name and in behalf of our respective constituents, fully and entirely ratify and confirm each and every of the said Articles of Confederation and perpetual Union, and all and singular the matters and things therein contained: And we do further solemnly plight and engage the faith of our respective constituents, that they shall abide by the determinations of the United States in Congress assembled, on all questions, which by the said Confederation are submitted to them. And that the Articles thereof shall be inviolably observed by the States we respectively represent, and that the Union shall be perpetual."
From the United States Constitution:
Article VI:
"All Debts contracted and Engagements entered into, before the Adoption of this Constitution, shall be as valid against the United States under this Constitution, as under the Confederation." (Emphasis added.)
From Samuel Johnson's Dictionary of 1755:
"Engagement...6. Obligation, motive."
From Webster's Dictionary of 1828:
"Engagement...1. Obligation by agreement or contract. Men are often more ready to make engagements than to fulfil them.
"Perpetual...1. Never ceasing; continuing forever in future time; destined to be eternal; as a perpetual covenant; a perpetual statute."
“As principals, in 1781, they created a general government as their agent through the “Articles of Confederation and perpetual Union...”
But the Articles of Confederation and their stated aspiration for a perpetual Union didn’t last very long.