Delete Instance.

Hey, I want to destroy the oldest entry of a array of gameobjects. how to ?

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class killer : MonoBehaviour {
 
     public Rigidbody2D collider2;
     public player script;
     public SpriteRenderer spriteRenderer;
     public Sprite sprite;
     public Collider2D collider1;
     
 
     // Use this for initialization
     void Update () {
         
     }
 
     void Awake()
     {
         
 
         
 
         DontDestroyOnLoad(this.gameObject);// to keep the player ragdol when die
     }
     
     private void OnTriggerEnter2D(Collider2D collision) // when hit the ground
     {
 
                 if (collision.tag == "ground")
         {
             script.enabled = false; // changes of sprite ect...
             spriteRenderer.sprite = sprite;
             collider2.constraints = RigidbodyConstraints2D.None;
             collider1.enabled = false;
 
             Application.LoadLevelAsync(Application.loadedLevelName); // reload the level
         }
         
     }
 
 }