Remove ad column from DOM in gmail and kill the remaining margin-right css property.

Hide_Gmail_Ads.js

// ==UserScript==
// @name       	Hide Gmail Ads
// @namespace  	http://userscripts.org/users/540155
// @description Remove ad column from DOM in gmail and kill the remaining margin-right css property.
// @match      	https://mail.google.com/
// @include		https://mail.google.com/*
// @include		https://mail.google.com
// @grant 		GM_addStyle
// @version    	0.1
// @copyright  	2014+, You
// ==/UserScript==
 
function removeAds() {
    var y3 = document.getElementsByClassName('y3');
	if (y3.length) {
	    y3[0].remove();
	    console.log('removed ad panel');
	}
}
window.onhashchange = removeAds;
window.setTimeout( removeAds, 5000 );
GM_addStyle('.if{margin-right: 0px !important;}');