How do you do that after destroying Stone with a golden pick, you cancel the task of renewing?

How do you do that after destroying Stone with a golden pick, you cancel the task of renewing?

public function onBreak(BlockBreakEvent $event){
$blok = $event->getBlock();
$gracz = $event->getPlayer();
$y = $blok->getFloorY();
$x = $blok->getFloorX();
$z = $blok->getFloorZ();
if($blok->getId() == 1){
$task = new Task($this, $event->getBlock()->getFloorX(), $event->getBlock()->getFloorY(), $event->getBlock()->getFloorZ());
$this->getServer()->getScheduler()->scheduleDelayedTask($task, 30);
}
}
}

Task.php
<?php

namespace StoneFarm;

use pocketmine\block\Block;
use pocketmine\block\Air;
use pocketmine\block\Stone;
use pocketmine\math\Vector3;
use pocketmine\scheduler\PluginTask;

class Task extends PluginTask{

private $z;
private $y;
private $x;
private $gracz;

public function __construct($gracz, $x, $y, $z){
parent::__construct($gracz);
$this->x = $x;
$this->y = $y;
$this->z = $z;
$this->gracz = $gracz;
}



public function onRun($currentTick){
$level = $this->gracz->getServer()->getLevelByName("world");
if($level->getBlock(new Vector3($this->x, $this->y, $this->z))->getId() == 0) {
$level->setBlock(new Vector3($this->x, $this->y, $this->z), new Stone());
}
}
}

 

please make your code clear next time by making it inside [PHP*] [/PHP*] (the * isn't included)