Redux Framework has an embedded demo. Click here to activate the sample config file

Problem solved! Helped official support. It was necessary to add the following code.

add_action( 'redux/loaded', 'remove_demo' );
/**
 * Removes the demo link and the notice of integrated demo from the redux-framework plugin
 */
if ( ! function_exists( 'remove_demo' ) ) {
    function remove_demo() {
        // Used to hide the demo mode link from the plugin page. Only used when Redux is a plugin.
        if ( class_exists( 'ReduxFrameworkPlugin' ) ) {
            remove_filter( 'plugin_row_meta', array(
                ReduxFrameworkPlugin::instance(),
                'plugin_metalinks'
            ), null, 2 );

            // Used to hide the activation notice informing users of the demo panel. Only used when Redux is a plugin.
            remove_action( 'admin_notices', array( ReduxFrameworkPlugin::instance(), 'admin_notices' ) );
        }
    }
}