Remove Bootstrap's validation icons : <h2>Explanation</h2>

<p>I'm trying to remove these <a href="https://getbootstrap.com/docs/4.2/components/forms/#validation" rel="noreferrer">Bootstrap's validation</a> icons ("x" and "check"), but I've look into everything and can't find where it is.</p>

<h2>Code</h2>

<p>You can also see in it this <a href="https://jsfiddle.net/at9enbmo/" rel="noreferrer">JSFiddle</a>.</p>

<p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
<div class="snippet-code">
<pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;link href="https://stackpath.bootstrapcdn.com/bootstrap/4.2.1/css/bootstrap.min.css" rel="stylesheet" /&gt;
&lt;script src="https://code.jquery.com/jquery-3.3.1.slim.min.js"&gt;&lt;/script&gt;
&lt;script src="https://stackpath.bootstrapcdn.com/bootstrap/4.2.1/js/bootstrap.min.js"&gt;&lt;/script&gt;
&lt;form class="was-validated"&gt;
  &lt;div class="form-group"&gt;
    &lt;select class="custom-select" required&gt;
      &lt;option value=""&gt;Open this select menu&lt;/option&gt;
      &lt;option value="1"&gt;One&lt;/option&gt;
      &lt;option value="2"&gt;Two&lt;/option&gt;
      &lt;option value="3"&gt;Three&lt;/option&gt;
    &lt;/select&gt;
    &lt;div class="invalid-feedback"&gt;Example invalid custom select feedback&lt;/div&gt;
  &lt;/div&gt;
&lt;/form&gt;</code></pre>
</div>
</div>
</p>

<p>Thanks in advance,<br>
Luiz.</p>
