JSFiddle - React, Tailwind, and code Playground

HTML

<p class="testing">Lorem Ipsum</p>
<p class="testing">Lorem Ipsum</p>

JavaScript

var elements = document.getElementsByClassName('testing');
var elementsLength = elements.length - 1;
for(var i = 0; i <= elementsLength ; i++)
{
    elements[i].classList.remove('testing');
}