For use with buttons in unity to start and scenes

StartGame.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.SceneManagement;
using UnityEngine.UI;

public class StartGame : MonoBehaviour
{
    public Button startButton;
    public Button mainMenuButton;

    private void Start()
    {
        //Calls the TaskOnClick/TaskWithParameters/ButtonClicked method when you click the Button
        startButton.onClick.AddListener(RestartGame);
        mainMenuButton.onClick.AddListener(MainMenu);
    }
    public void RestartGame()
    {
        SceneManager.LoadScene("SampleScene");
        PlayerPrefs.DeleteAll();
    }

    public void MainMenu()
    {
        SceneManager.LoadScene("Start");
        PlayerPrefs.DeleteAll();
    }
}