"Welcome Google Chat" Banner Remover - User JS for Greasemonkey / Tampermonkey.

remove-google-chat-welcome-banner.user.js

// ==UserScript==
// @name         Welcome Google Chat Remover
// @version      0.1
// @description  Removes Google Chat's Welcome banner that is annoying.
// @author       Gustavo Moraes (gustavomdsantos@pm.me)
// @match        https://mail.google.com/*
// @icon         data:image/png;base64,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
// @require      http://ajax.googleapis.com/ajax/libs/jquery/1.7.2/jquery.min.js
// @require      https://gist.github.com/raw/2625891/waitForKeyElements.js
// @grant        GM_addStyle
// ==/UserScript==

(function() {
    'use strict';

    function removeWelcomeBanner (jNode) {
        $(".aB7")[0].remove();
        $(".bgt").css("margin-bottom", "auto");
    }

    waitForKeyElements (".aB7", removeWelcomeBanner);
})();

Welcome-Google-Chat-Remover-icon.svg

<svg xmlns="http://www.w3.org/2000/svg" width="48" height="48"><path fill="#00ac47" d="M11.43 25.9V10.3H4.62C2.6 10.3.99 11.91.99 13.92v32.25a1.82 1.82 0 0 0 3.1 1.28l7.5-7.5h21.35c2 0 3.63-1.62 3.63-3.62v-6.82h-21.5c-2 0-3.64-1.62-3.64-3.63z"/><path fill="#5bb974" d="M43.38 0h-28.3c-2.01 0-3.64 1.62-3.64 3.63v6.66h21.5c2 0 3.63 1.62 3.63 3.63v15.6h6.81c2.01 0 3.63-1.63 3.63-3.64V3.63c0-2-1.62-3.63-3.63-3.63Z"/><path fill="#00832d" d="M32.94 10.3h-21.5v15.58c0 2 1.62 3.63 3.62 3.63h21.5V13.93c0-2-1.62-3.64-3.62-3.64z"/><path fill="none" stroke="red" stroke-linecap="round" stroke-width="2" d="M11.44 10.3 36.56 29.5M36.56 10.3 11.44 29.5"/></svg>