Disable google's automatic sign-in, yes, as simple as that
// ==UserScript==
// @name Uncheck Google Stay Signed In
// @namespace ugssi
// @description Disable google's automatic sign-in, yes, as simple as that
// @include http://accounts.google.tld/*
// @include https://accounts.google.tld/*
// @version 1.0
// @grant none
// ==/UserScript==
var chkbox = document.getElementById('PersistentCookie');
chkbox.removeAttribute('checked');