How do you make a script to close out this pop up menu?

Title explains it all, I suck at coding some things. I’ve been trying to do stuff for a while, and still can’t get it.

Here is code:

using UnityEngine;
using System.Collections;

public class Popup : MonoBehaviour {
	public Rect windowRect = new Rect(200, 200, 1200, 500);
	void OnGUI() {
		windowRect = GUI.Window(0, windowRect, DoMyWindow, "Controls: WASD/Arrow Keys: Move | R: Reset| Esc: Quit Game" +
			" || New Features: This Popup Of Course.| Day And Night System.|| Running Version 3");
	}
	void DoMyWindow(int windowID) {
		if (GUI.Button (new Rect (10, 20, 100, 20), "Ok, Whatever"))
			show windowRect = false;
		
	}
}

You may just disable the Popup script.

void DoMyWindow(int windowID) 
 {
     if (GUI.Button(new Rect(10, 20, 100, 20), "Ok, Whatever"))
         this.enabled = false;
 }