update $wpdb one query

Try removing the $wpdb->prepare.

$wpdb->query("UPDATE wp_postmeta SET meta_value = meta_value - 1  WHERE post_id= 9999 AND meta_key = 'point_user'");

Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)