Sure they can. All it takes is repealing the statute just like they passed it in the first place. Like it or not, non-seq, laws may be repealed - even those that claim to be unrepealable.
And both said that first and foremost the purpose of the expedition was the peaceful landing of supplies, and that force was to be used only if the landing was opposed.
Wrong. One actively said that force WILL be used right then and there if the landing is opposed, the other passively said that force WILL NOT be used if the landing is permitted while giving not the slightest indication of when, where, how or if force would be used if entry was denied. YOU keep ignoring that fact in your attempt to twist the meaning into something it wasn't.
So can constitutions.
[The] fundamental principle of republican government, which admits the right of the people to alter or abolish the established Constitution, whenever they find it inconsistent with their happiness.
Alexander Hamilton, Federalist No 78, "The Judiciary Department"
Utter nonsense. Once title was passed to the federal government then South Carolina had no claim to it and no control over it. The idea that they could suddenly take it back without recourse is ridiculous. Constitutionally only Congress could exercise authority over land obtained with consent of legislature for forts, etc. Once South Carolina gave it up only Congress could give it back.
Wrong.
Sorry, you're wrong. Both identified peaceful resupply and the focus for the expedition with force to be used only if the resupply was opposed.