function pc_admin_index_notice(){

    global $pagenow;

    if ( !($pagenow == 'index.php') ) {
    	return;
	}

    $user = wp_get_current_user();

    if ( !in_array( 'administrator', (array) $user->roles ) ) {
    	return;
    }

    echo '<div class="notice notice-info is-dismissible">
          <p>Click on <a href="edit.php">Posts</a> to start writing.</p>
          <h1>HELLO WORLD!! This page is index.php and you are Administrator</h1>
         </div>';
}

add_action('admin_notices', 'pc_admin_index_notice', 11);


// ======================================

 function pc_delete_all_admin_notices() {
    $admin_user_ID_with_notices = '1';

 	$user = wp_get_current_user();
    $user_data = $user->data;

    if ( in_array( 'administrator', (array) $user->roles )
    	&& $user_data->ID == $admin_user_ID_with_notices ) {
    		return;
    }

    global $wp_filter;

	$wp_filter['admin_notices'] = null;

}

add_action('init', 'pc_delete_all_admin_notices', 999);