code: public function onAfterDelete() {
  
  		parent::onAfterDelete();
  		$fusion = FusionTag::get()->byID($this->owner->FusionTagID);
  		$types = unserialize($fusion->TagTypes);
  		unset($types[$this->owner->ClassName]);
  		$fusion->TagTypes = !empty($types) ? serialize($types) : null;
  		$fusion->write();
  	}
docs: Update the fusion tag to remove this tag type.