Add Filter to Ignore a Post/Page or a Number of Post/Pages

you can use pre_get_posts filter hook and set the post__not_in parameter of the query ex:

function exclude_from_search_filter($query) {
        if ( !$query->is_admin && $query->is_search) {
                $query->set('post__not_in', array(40, 9) ); // id of page or post
        }
        return $query;
}
add_filter( 'pre_get_posts', 'exclude_from_search_filter' );