pocketmine\item\Item::clearCustomBlockData PHP Method

    public function clearCustomBlockData()
    {
        if (!$this->hasCompoundTag()) {
            return $this;
        }
        $tag = $this->getNamedTag();
        if (isset($tag->BlockEntityTag) and $tag->BlockEntityTag instanceof CompoundTag) {
            unset($tag->display->BlockEntityTag);
            $this->setNamedTag($tag);
        }
        return $this;
    }