test.js

// remove the "Footnote" menu item
TXTextControl.addEventListener("contextMenuOpening", (e) => {

	// check if e.items contains an entry where property text == "Insert"
	const index = e.items.findIndex((i) => i.text === "Insert");

	// check if e.items[index].items contains an entry where property text == "Footnote"
	const index2 = e.items[index].items.findIndex((i) => i.text === "Footnote");

	// if so, remove it
	if (index2 > -1) {
		e.items[index].items.splice(index2, 1);
	}

})