Experimente o Greasemonkey : e crie um novo script
// ==UserScript==
// @name bleh somthing
// @description ---s
// @version 1.0
// @license Public Domain
// @grant none
// @include http*://*.DOMAIN.com/*
// @include http://www.DOMAIN.com/.*
// ==/UserScript==
rem = document.querySelector('.annotation');
rem.parentNode.removeChild(rem);