To change the document root of the main domain in cPanel, log in to your cPanel account and open the Domains section to locate your primary domain. If your hosting provider permits, click Manage, update the Document Root to the desired folder—such as a subdirectory within public_html—and save the changes. If direct editing is not allowed, create the new directory manually, move your website files there, and adjust any configuration files or .htaccess rules as needed. Afterward, check file permissions and test the website to ensure it loads correctly from the new document root.