You can hide spinner in the ProgressButton by setting the e-hide-spinner property to cssClass.
// Initialize ProgressButton component
var progressBtn = new ej.splitbuttons.ProgressButton({content: 'Progress', enableProgress: true, cssClass: 'e-hide-spinner'});
// Render initialized ProgressButton.
progressBtn.appendTo('#progressbtn');<!DOCTYPE html><html lang="en"><head>
<title>EJ2 ProgressButton</title>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta name="description" content="This demo for Essential JS2 Progress button has progress indicator and spinner. It supports texts, icons, styles, sizes, positions, and its customization.">
<meta name="author" content="Syncfusion">
<link href="//cdn.syncfusion.com/ej2/21.2.3/ej2-base/styles/material.css" rel="stylesheet">
<link href="//cdn.syncfusion.com/ej2/21.2.3/ej2-buttons/styles/material.css" rel="stylesheet">
<link href="//cdn.syncfusion.com/ej2/21.2.3/ej2-popups/styles/material.css" rel="stylesheet">
<link href="//cdn.syncfusion.com/ej2/21.2.3/ej2-splitbuttons/styles/material.css" rel="stylesheet">
<link href="styles.css" rel="stylesheet">
<script src="https://cdn.syncfusion.com/ej2/21.2.3/dist/ej2.min.js" type="text/javascript"></script>
</head>
<body>
<div id="container">
<button id="progressbtn"></button>
</div>
<script>
var ele = document.getElementById('container');
if(ele) {
ele.style.visibility = "visible";
}
</script>
<script src="index.js" type="text/javascript"></script>
</body></html>