1. Attack ClearSaveButton function to your delete Button.
Name Spaces maybe requires :-
using UnityEngine;
using System.Collections;
using UnityEngine.UI;
using System.Runtime.Serialization.Formatters.Binary;
using System;
using System.IO;
public void ClearSaveButton()
{
ClearDataCanvas.enabled = false;
if (File.Exists (Application.persistentDataPath + "/playerInfo.dat"))
{
File.Delete(Application.persistentDataPath + "/playerInfo.dat");
Application.Quit ();
}
}