Colliding with other objects. How to stop it?

Hello… im stuck with this problem. My problem is when i pick up some object and place it and pick up some another objects after that when i collide with another object my button change to pickup and when i click it the other obect stick to another object that the player holding… if you dont understand… you can check my video (- YouTube) please help me :(n

My scipt:

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class wallsPickup : MonoBehaviour {

public GameObject onHand;
public GameObject unParent;
public bool isCarrying;
public bool isPickUp;
public GUISkin skin = null;
public Texture2D btnPlace = null;
public Texture2D btnPickUp = null;

void Start () {

	isCarrying = false;
	isPickUp = false;

}
	
void OnCollisionStay (Collision col) {

	if(col.gameObject.tag == "Player")
	{

		isPickUp = true;

	}

}

void OnCollisionExit () {

	isPickUp = false;
	isCarrying = false;

}

void OnGUI() {

	GUI.skin = skin;

	if (isCarrying == true) {
		if (GUI.Button (new Rect (Screen.width - 200,Screen.height - 200,160,160), btnPlace)) { 
			this.transform.parent = unParent.transform;
			isPickUp = false;
			print("clicked");
		}
	}

	if (isPickUp == true) {
		if (GUI.Button (new Rect (Screen.width - 200,Screen.height - 200,160,160), btnPickUp)) { 
			this.transform.parent = onHand.transform;
			isCarrying = true;
			isPickUp = false;
		}
	}
}

}

Disable the collider.