Replacing A GameObject

I've been trying to make a changeable character scene where on clicking 'next' button the character changes I am able to generate the prefab but unfortunately the earlier prefab is never destroyed. What am I doing Wrong, Thanks for the help in advance.

 using UnityEngine;
 using System.Collections;
 
 public class character_Set : MonoBehaviour {
     public GameObject character1;
     public GameObject character2;
     public GameObject cCharacter;
     public int characternum = 1;
     private bool startup = true;
         // Use this for initialization
     void Start() {
     
         cCharacter = Instantiate (character1) as GameObject;
 
         }
     // Update is called once per frame
     void Update () {
 
     }
     void OnGUI()
     {
         if (GUI.Button (new Rect (50, 50, 70, 40), "Next")) {
             Destroy(cCharacter);
             ChangeCharacters();
             }
 
     }
     void ChangeCharacters(){
 
         if (characternum == 1) {
             cCharacter = Instantiate(character2) as GameObject;
             characternum = 2;
         }
         if (characternum == 2) {
             cCharacter = Instantiate(character1) as GameObject;
             characternum =1;
         }
     }
 }