remove_main_site_link.php

<?php
function print_custom_style (){

	if(!is_super_admin()){
		echo '<style> #wp-admin-bar-blog-1 {display: none !important} </style>';
	}

}
//For wp-admin
add_action('admin_head', 'print_custom_style');

//For frontend
add_action('wp_head', 'print_custom_style');