pocketmine\entity\Entity::setDataFlag PHP Method

    public function setDataFlag($propertyId, $id, $value = true, $type = self::DATA_TYPE_BYTE)
    {
        if ($this->getDataFlag($propertyId, $id) !== $value) {
            $flags = (int) $this->getDataProperty($propertyId);
            $flags ^= 1 << $id;
            $this->setDataProperty($propertyId, $type, $flags);
        }
    }

 public function remove(Entity $entity)
 {
     if ($entity instanceof Player) {
         $pk = new MobEffectPacket();
         $pk->eid = 0;
         $pk->eventId = MobEffectPacket::EVENT_REMOVE;
         $pk->effectId = $this->getId();
         $entity->dataPacket($pk->setChannel(Network::CHANNEL_WORLD_EVENTS));
     }
     if ($this->id === Effect::INVISIBILITY) {
         $entity->setDataFlag(Entity::DATA_FLAGS, Entity::DATA_FLAG_INVISIBLE, false);
         $entity->setDataProperty(Entity::DATA_SHOW_NAMETAG, Entity::DATA_TYPE_BYTE, 1);
     }
 }