Lazy Updater

DestroyComponentsAtY.cs

using UnityEngine;
using System.Collections.Generic;

public class DestroyComponentsAtY : LazyUpdater<Component>
{
  public float YLevel = -100;

  private bool _allBelow;

  public DestroyComponentsAtY(IReadOnlyList<Component> objects, int updateCount = 1) : base(objects, updateCount)
  {
  }

  protected override void UpdateStart()
  {
    _allBelow = true;
  }

  protected override void UpdateEnd()
  {
    if (_allBelow)
      MarkDone();
  }

  protected override void UpdateInternal(Component instance, IReadOnlyList<Component> instances)
  {
    if (instance.transform.position.y < YLevel)
      GameObject.Destroy(instance.gameObject);
    else
      _allBelow = false;
  }
}

LazyUpdater.cs

using System.Collections.Generic;
using System.Collections;

public abstract class LazyUpdater<T>
{
  public bool IsDone => _isDone;

  private int _currentIndex;
  private int _updateCount;
  private IReadOnlyList<T> _objectsReadonly;
  private bool _isDone;

  public LazyUpdater(IReadOnlyList<T> objects, int updateCount = 1)
  {
    _updateCount = updateCount;
    _objectsReadonly = objects;
  }

  public void Update()
  {
    for (int i = 0; i < _updateCount; ++i)
    {
      if (_currentIndex < _objectsReadonly.Count)
      {
        if (_currentIndex == 0)
          UpdateStart();

        UpdateInternal(_objectsReadonly[_currentIndex], _objectsReadonly);
      }

      _currentIndex += 1;
      if (_currentIndex >= _objectsReadonly.Count && _objectsReadonly.Count > 0)
      {
        _currentIndex = 0;
        UpdateEnd();
      }
    }
  }

  public IEnumerator RunAsync()
  {
    while (!IsDone)
    {
      Update();
      yield return null;
    }
  }

  public void MarkDone()
  {
    _isDone = true;
  }

  protected abstract void UpdateStart();
  protected abstract void UpdateInternal(T instance, IReadOnlyList<T> instances);
  protected abstract void UpdateEnd();
}