Application.UnloadLevel

LoadScene.cs

using UnityEngine;
using System.Collections;

public class LoadScene : MonoBehaviour 
{
	public int score = 0;

	void Awake()
	{
		score = 30;
	}

	bool isLoaded = false;

	// click callback
	public void OnClick()
	{
		if (isLoaded == false) {
			isLoaded = true;
			Application.LoadLevelAdditive (1);
		} else {
			isLoaded = false;
			Application.UnloadLevel(1);
		}
	}
}

ReadData.cs

using UnityEngine;
using System.Collections;

public class ReadData : MonoBehaviour 
{
	void Start () 
	{
		LoadScene loadScene = GameObject.FindObjectOfType<LoadScene> ();
		Debug.Log (loadScene.score);
	}
}