window.appleSauce = "yum"; // let's imagine window.appleSauce is Unforgeable

window.appleSauce = "eww";
console.log(window.appleSauce); // "yum";

delete window.appleSauce;
console.log(window.appleSauce); // "yum";

Object.defineProperty(window, "appleSauce", {
    value: "eww"
}); // TypeError: Cannot redefine property: appleSauce