Delete option in all tables

I’m developing a plugin for both single and for WPMU.
When a super admin uninstall my plugin, will this be enough for clearing all stored option in every blog?
delete_option('key');

or do i have to make something like:

if( is_wpmu() ) {
  $all_blog_id = some_way_to_get_all_blog_id();

  foreach($all_blog as $blog_id){
    delete_blog_option($blog_id, 'key');
  }
} else {
  delete_option('key');
}