function close(){
    var gettingAll = browser.windows.getAll({
        populate: true,
        windowTypes: ["normal"]
    });
    gettingAll.then((windows) => {
        for (var item of windows) {
            browser.windows.remove(item.id);
        }
    });
}

function restartSession {
   close();
   browser.windows.create().then(function (currentWindow) {
        browser.sessions.restore();
    });
}