pocketmine\inventory\BaseInventory::clear PHP Method

    public function clear($index, $send = true)
    {
        if (isset($this->slots[$index])) {
            $item = Item::get(Item::AIR, null, 0);
            $old = $this->slots[$index];
            $holder = $this->getHolder();
            if ($holder instanceof Entity) {
                Server::getInstance()->getPluginManager()->callEvent($ev = new EntityInventoryChangeEvent($holder, $old, $item, $index));
                if ($ev->isCancelled()) {
                    $this->sendSlot($index, $this->getViewers());
                    return false;
                }
                $item = $ev->getNewItem();
            }
            if ($item->getId() !== Item::AIR) {
                $this->slots[$index] = clone $item;
            } else {
                unset($this->slots[$index]);
            }
            $this->onSlotChange($index, $old, $send);
        }
        return true;
    }