JavaScript Tutorial

.removeClass()

<!DOCTYPE html>
<html>
<head>
    <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
    <script>
    $(document).ready(function(){
      $("button").click(function(){
        $("p").removeClass("intro");
      });
    });
    </script>
<style>
    .intro {
      font-size: 120%;
      color: red;
    }
</style>
</head>
<body>
    <h1>This is a heading</h1>
    <p class="intro">This is a paragraph.</p>
    <p class="intro">This is another paragraph.</p>
    <button>Remove the "intro" class from all p elements</button>
</body>
</html>