<!DOCTYPE html>
<html>
<head>
<style>
.democlass {
color: red;
}
</style>
</head>
<body>
<h1 class="democlass">Hello World</h1>
<p id="demo">Click the button to remove the class attribute from the h1 element.</p>
<button onclick="myFunction()">Try it</button>
<script>
function myFunction() {
document.getElementsByTagName("H1")[0].removeAttribute("class");
}
</script>
</body>
</html>