How to destroy two cloned cards when matched in memory card game?

using System.Collections.Generic; using UnityEngine; using System.Collections; using UnityEngine.SceneManagement;

public class SceneController_animal : MonoBehaviour {
public GameObject teacher;

 public const int gridRows = 2;
 public const int gridCols = 4;
 public const float offsetX = 4f;
 public const float offsetY = 4.8f;

 [SerializeField]
 private MainCard_animal originalCard;
 
 [SerializeField]
 private Sprite[] images;

 private void Start()
 {
     Vector3 startPos = originalCard.transform.position; //The position of the first card. All other cards are offset from here.
     int[] numbers = { 0, 0, 1, 1, 2, 2, 3, 3 };
     numbers = ShuffleArray(numbers);

     for(int i = 0; i < gridCols; i++)
     {
         for(int j = 0; j < gridRows; j++)
         {
             MainCard_animal card;
             if (i == 0 && j == 0)
             {
                 card = originalCard;

             }
             else
             {

                 card = Instantiate(originalCard) as MainCard_animal;

             }

             int index = j * gridCols + i;
             int id = numbers[index];
             card.ChangeSprite(id, images[id]);

             float posX = (offsetX * i) + startPos.x;
             float posY = (offsetY * j) + startPos.y;

             card.transform.position = new Vector3(posX, posY, startPos.z);

         }

     }

 }


 private int[] ShuffleArray(int[] numbers)
 {
     int[] newArray = numbers.Clone() as int[];
     for(int i = 0; i < newArray.Length; i++)
     {
         int tmp = newArray[i];
         int r = Random.Range(i, newArray.Length);
         newArray[i] = newArray[r];
         newArray[r] = tmp;
     }
     return newArray;
 }

 private MainCard_animal _firstRevealed;
 private MainCard_animal _secondRevealed;

 private int _score = 0;
 [SerializeField] private TextMesh scoreLabel;
 
 public bool canReveal
 {
     get { return _secondRevealed == null; }
 }


 public void CardRevealed(MainCard_animal card)
 {
     if(_firstRevealed == null)
     {
         _firstRevealed = card;

     }
     else
     {
         _secondRevealed = card;
         StartCoroutine(CheckMatch());
     }
 }


 private IEnumerator CheckMatch()
 {
     if(_firstRevealed.id == _secondRevealed.id)
     {
         _score++;
         scoreLabel.text = "Score: " + _score;

     Destroy(_firstRevealed);
     Destroy(_secondRevealed);

     }
     else
     {
         yield return new WaitForSeconds(0.5f);
         _firstRevealed.Unreveal();
         _secondRevealed.Unreveal();
     }

     _firstRevealed = null;
     _secondRevealed = null;

     if (_score == 4)
     {


     }
 }

}