delete Object

    delete Object.prototype.constructor;
    delete Object;


    console.log(window.__proto__.__proto__.__proto__.constructor); // undefined
    // console.log(Object); // undefined

    var frame = document.createElement('frame');
    document.all[0].appendChild(frame);

    var Object = frames[0].Object;
    document.all[0].removeChild(frame);
    console.log(Object);