disable a wp javascript on live website, but not on wp-admin page

You can do a simple is_admin() check before dequeuing your script like below:

Code:

add_action( 'wp_print_scripts', 'my_deregister_javascript', 100 );

function my_deregister_javascript() {

   if ( !is_admin() )
       wp_deregister_script( 'wp-embed' );
   }

}