GM_script_Yahoo_Mail_Improvements.user.js

// ==UserScript==
// @name        Yahoo Mail Improvements
// @namespace   YahooMail
// @description Improve experience of using Yahoo Mail
// @include     https://us-mg5.mail.yahoo.com/neo/*
// @version     1
// @grant       none
// ==/UserScript==

function addGlobalStyle(css) {
    var head, style;
    head = document.getElementsByTagName('head')[0];
    if (!head) { return; }
    style = document.createElement('style');
    style.type = 'text/css';
    style.innerHTML = css;
    head.appendChild(style);
}


(function() 
 {
     addGlobalStyle('.tc .list-view-item-date-label { display: none; }');
})();