Code

var menu = document.getElementById("menu");
menu.style.display = "none";
menu.oncontextmenu = function () { return false };
menu.onclick = function(){
	diagram.removeItem(node);
	menu.style.display = "none";
}

var node = null;

function onNodeClicked(sender, args) {
	if (args.mouseButton == 2) {
		var diagramView = MindFusion.Diagramming.DiagramView.find("diagram");
		var position = diagramView.element.getBoundingClientRect();
		var point = diagramView.docToClient(args.mousePosition);
		menu.style.display = "block";
		menu.style.left = `${position.left + point.x}px`;
		menu.style.top = `${position.top + point.y}px`;
		node = args.node;
	}
}