c# how to create secure folder (password protected)

I Want to create secure folder..Client will not able to open my folder. 
i research and find below code...
but this code not help me because i can change easily and allow user to open by properties
option and go advance button here my current user i edit permission deny to allow...this is not secure way 
to create folder...please help me to create secure so client fully 100% not able to open folder
using System;using System.IO;using System.Security.AccessControl;namespace FileSystemExample
{class DirectoryExample
    {publicstaticvoid Main()
        {try
            {string DirectoryName = "TestDirectory";

                Console.WriteLine("Adding access control entry for "+ DirectoryName);// Add the access control entry to the directory.
                AddDirectorySecurity(DirectoryName, @"MYDOMAIN\MyAccount", FileSystemRights.ReadData, AccessControlType.Allow);

                Console.WriteLine("Removing access control entry from "+ DirectoryName);// Remove the access control entry from the directory.
                RemoveDirectorySecurity(DirectoryName, @"MYDOMAIN\MyAccount", FileSystemRights.ReadData, AccessControlType.Allow);

                Console.WriteLine("Done.");
            }catch (Exception e)
            {
                Console.WriteLine(e);
            }

            Console.ReadLine();
        }

        // Adds an ACL entry on the specified directory for the specified account. publicstaticvoid AddDirectorySecurity(string FileName, string Account, FileSystemRights Rights, AccessControlType ControlType)
        {// Create a new DirectoryInfo object.
            DirectoryInfo dInfo = new DirectoryInfo(FileName);// Get a DirectorySecurity object that represents the  // current security settings.
            DirectorySecurity dSecurity = dInfo.GetAccessControl();// Add the FileSystemAccessRule to the security settings. 
            dSecurity.AddAccessRule(new FileSystemAccessRule(Account,
                                                            Rights,
                                                            ControlType));// Set the new access settings.
            dInfo.SetAccessControl(dSecurity);

        }

        // Removes an ACL entry on the specified directory for the specified account. publicstaticvoid RemoveDirectorySecurity(string FileName, string Account, FileSystemRights Rights, AccessControlType ControlType)
        {// Create a new DirectoryInfo object.
            DirectoryInfo dInfo = new DirectoryInfo(FileName);// Get a DirectorySecurity object that represents the  // current security settings.
            DirectorySecurity dSecurity = dInfo.GetAccessControl();// Add the FileSystemAccessRule to the security settings. 
            dSecurity.RemoveAccessRule(new FileSystemAccessRule(Account,
                                                            Rights,
                                                            ControlType));// Set the new access settings.
            dInfo.SetAccessControl(dSecurity);

        }
    }
      

qasim