<?php
$id = "3414a43";
$str = "[ta #12286152] c-d0-231-34 drop [#3414a43]";
$result = preg_replace('~\[[^][]*' . $id . '[^][]*]~', '', $str); echo $result;
PD9waHAKCiRpZCA9ICIzNDE0YTQzIjsKJHN0ciA9ICJbdGEgIzEyMjg2MTUyXSBjLWQwLTIzMS0zNCBkcm9wIFsjMzQxNGE0M10iOyAKJHJlc3VsdCA9IHByZWdfcmVwbGFjZSgnflxbW15dW10qJyAuICRpZCAuICdbXl1bXSpdficsICcnLCAkc3RyKTsKZWNobyAkcmVzdWx0Ow==