How to close a menu by clicking a cloned button inside it?

I have a menu that gets populated at runtime with buttons whose text components are based on objects that the game manager has in its databases. At the start, the menu is empty:

![alt text][1]

See that "A" graphic? It's a button called Button_Magic_DropDown that activates/deactivates the panel called Panel_MagicMenu. At runtime, regardless of whether the panel is active, its child panel Empty_Inset_MagicMenu gets 6 children, which are all instances of the button prefab, Button_BattleMenu. When one of these buttons are clicked, I want the panel called Panel_MagicMenu to get deactivated. See image below:

![alt text][2]

What I am struggling with is deactivating [the parent panel of a ] panel that a button sits in when it is clicked. I am trying to do this by getting the second parent programmatically and deactivating it. Here is the script containing that function OnClickDeactivatePanel(), which I am assigning in the button prefab:

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class BattleUI : MonoBehaviour
 {
     public void ToggleActive(GameObject panel)
     {
         panel.SetActive(!panel.activeInHierarchy);
     }
 
     public void OnClickDeactivatePanel()
     {
         //On click, deactivates the panel that the button sits in, two parents up
         GameObject secondParent = gameObject.transform.parent.parent.gameObject;
         //Debug.Log("Second parent is " + secondParent);
         secondParent.SetActive(false);
     }
 }

As you can guess, this didn't work. Unity is unable to identify the parents of an instanced object this way. I get a null-reference error. What can I do?