How do you change the int of an object in the scene with an instantiated button?

I am fairly new to unity so forgive me if this is a very easily solved problem. So basically my problem is that you can't apply something from the scene to a slot on a prefab. Since I can't do this I have to change the int (health) on my enemy through its prefab, which I then have no way to switch back to its original value without going into the prefab and changing it back. So what I want to know is how I could link the button to instantiate and specifically have the enemy in the scene as the thing it will subtract health from. here are my current button scripts (does not include the one I use to instantiate it because that script is overly complicated and long and you will probably laugh at me for overcomplicating things.):

script on enemy:

 using UnityEngine;
 using System.Collections;
 
 public class EnemyHealth : MonoBehaviour{
     
     public int health = 5;
 
     public void remove(int value){
         health -= value;
         
         if(health <= 0){
             health = 0;
             Application.LoadLevel("Lose Screen");
         }   
     } 
 }

script on button:

 using UnityEngine;
 using System.Collections;
 public class ButtonInteraction : MonoBehaviour{
     
     public EnemyHealth _enemyHealth;
     
     public void DamageButton(int damage){
         _enemyHealth.remove(damage);
     }
     
 }

I assume that the answer to this is probably going to be a GetComponent or GameObject.Find thing, but I wouldn't know how to go about stuff like that exactly. Could you help me with this?