delete_user_meta Delete one value out of array

Thanks yo Howdy_McGee, Here is working code.

// Remove favorite authors from current users DB
function fav_author_remove_user(){
    check_ajax_referer( 'fav_authors_obj_ajax', 'security' );
    $remove_this_author = $_POST['clicked_author_id'];

    if ( current_user_can( 'edit_posts' ) ){
        $user_id = fav_authors_get_user_id();

        $author_list = get_user_meta( $user_id, FAV_AUTHORS_META_KEY, true );
        //print_r($author_list);
        $author_saved = array_search($remove_this_author, $author_list);
        if( FALSE !== $author_saved ){
            // Remove $author_saved
            unset($author_list[$author_saved]);
            $author_arr = ( is_array( $author_list ) ) ? $author_list : array( $author_list );
            update_user_meta( $user_id, FAV_AUTHORS_META_KEY, $author_arr );
        }
    }
}
add_action( 'wp_ajax_remove_fav_author_id', 'fav_author_remove_user' );