That is not an accurate summary. It is misleading.
The purpose of the 1787 federal convention was recommended by the delegates to the Annapolis convention of 1786.
Delegates informally discussed a wider convention and resolved on September 14th 1786 to ask their states for a general meeting to take into consideration the situation of the United States, to devise other such provisions as shall appear to them necessary to render the constitution of the federal government adequate to the exigencies of the Union, and to report such an Act for that purpose to the United States in Congress assembled.
In 1787, as in a future state convention, the authority of state delegates will be limited and defined by their states. Neither convention did/can “throw out” anything.
Wow. Hu knew.