Why can't I destroy my Prefab ? Please help I'm new.

 using System.Collections;
 using System.Collections.Generic;
 
 public class FDEnviroment : MonoBehaviour {
 //Variables Start-------------------------------------------------------------------
     public enum State
     {
         Idle,
         Initialize,
         Setup,
         Spawn
     }
     
     public State state;
        public GameObject[] PlanetSpawanLocation;
     public GameObject[] PlanetObjectPrefab;
     PlayerStats MyStats;
     private int MyAccountChk;
 //Variables End----------------------------------------------------------------------_____________________________________    
     
     void Awake()
     {
         
         state = FDEnviroment.State.Initialize;
         
         //Instantiate(PlanetObject,new Vector3(-0.050f,0.15f,0.59f),Quaternion.identity);
         // this is needed only if you want to load from the assets file
         //PlanetObject = (GameObject)Resources.Load("MyPlanet", typeof(GameObject)); 
     }
     
     // Use this for initialization
     IEnumerator Start ()
     
     {
         while(true)    {
             switch(state){
             case State.Initialize:
                 Initialize();
                 break;
             case State.Setup:
                 Setup();
                 break;
             case State.Spawn:
                 Spawn();
                 break;
             }
             yield return 0;
         }
         
         
         //    Instantiate(PlanetObject,new Vector3(-0.050f,0.15f,0.59f),Quaternion.identity);
     }
         
     private void Initialize()
     {   Debug.Log(" We are in the Initialize function");
         if(!checkForPlanetPrefabs())
             return;
         if(!checkForSpawnPoints())
             return;
         state = FDEnviroment.State.Setup;        
     
     }
         
         private void Setup()
     {   Debug.Log(" We are in the setup function");
         state = FDEnviroment.State.Spawn;
         
     }
     
         private void Spawn()
     {   Debug.Log(" We are in the spawn function");
         
         GameObject[] ObjItem = AvailableSpawnPoints();
         for(int cnt = 0; cnt < ObjItem.Length; cnt++)
         {
             GameObject it = Instantiate(PlanetObjectPrefab[Random.Range(0,PlanetObjectPrefab.Length)],ObjItem[cnt].transform.position,
                                                                                 Quaternion.identity)as GameObject;
             it.transform.parent = ObjItem[cnt].transform;
         }
         
         state = FDEnviroment.State.Idle;
         
     }
     
     // check to see if we have at least one prefab t0 spawn
     private bool checkForPlanetPrefabs()
     {
         if(PlanetObjectPrefab.Length > 0)
         return true;
         else
             return false;
     }
     
     // check to see if we have at least one spawn point to spawn object
     
         private bool checkForSpawnPoints()
     {
         if(PlanetSpawanLocation.Length > 0)
             return true;
         else
             return false;
     }
     
     
     // Generate a list of available spawnpoints that do not have any objects childed to it
     private GameObject[] AvailableSpawnPoints()
     {
         List ObjItem = new List ();
         for(int cnt = 0; cnt ();
             MyAccountChk = MyStats.Account;
             if(MyAccountChk > 300)
         {
             PlanetDestroy();
         }
             
     }
 }