You can hide spinner in the ProgressButton by setting the e-hide-spinner property to cssClass.
import { ProgressButton } from '@syncfusion/ej2-splitbuttons';
let progressBtn: ProgressButton = new ProgressButton({ content: 'Progress', enableProgress: true, cssClass: 'e-hide-spinner' });
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://cdnjs.cloudflare.com/ajax/libs/systemjs/0.19.38/system.js"></script>
<script src="systemjs.config.js"></script>
</head>
<body>
<div id='loader'>LOADING....</div>
<div id='container'>
<button id='progressbtn'></button>
</div>
</body>
</html>