JSFiddle - React, Tailwind, and code Playground

HTML

<div class="shop" id="shop">
        <div id="1" class="item"> 
          <div class="details">
            <div class="buttons">
              <div id="1" class="quantity">1 
            </div>
          </div>
        </div>
        <div id="2" class="item"> 
          <div class="details">
            <div class="buttons">
              <div id="2" class="quantity">2
            </div>
          </div>
        </div>
</div>

JavaScript

document.querySelector('.item:nth-child(2) .quantity').innerText="";