我需要将我创建的文件夹的访问权限更改为非只读

Question

我正在创建一个文件夹，该文件夹是人们在文本框中键入的电话号码。然后，我将使用来自其他文本框的信息在该文件夹内创建一个文本文件，但不会创建该文本文件，因为使用电话号码创建的文件夹设置为“只读”。

Phonenumber = phonereg_textbox.Text;
FirstName = firstname_textbox.Text;
LastName = lastname_textbox.Text;
Email = email_textbox.Text;
Password = Passwordone; 
DateOFBirth = selectedDate;
//check if the phonenumber exists if it does then show a message, if it does not exist then create
if (!Directory.Exists(@"C:\Users\mogee\Desktop\2019Form Files\Registered Users\" + Phonenumber))
{
    Directory.CreateDirectory(@"C:\Users\mogee\Desktop\2019Form Files\Registered Users\" + Phonenumber);

    using (StreamWriter sw = File.CreateText(@"C:\Users\mogee\Desktop\2019Form Files\Registered Users\" + Phonenumber))
    {
        sw.WriteLine("Hello");
        sw.WriteLine("And");
        sw.WriteLine("Welcome");
    }
    MessageBox.Show("File Created");


    //Close page and open Register Email Sent page
    RegisterEmailSent RES = new RegisterEmailSent();
    RES.Show();
    this.Close();
}
else
{
    MessageBox.Show("File Already Exists");
    RegisterEmailSent RES = new RegisterEmailSent();
    RES.Show();
    this.Close();
}

在尝试创建文本文件时，我只会收到错误消息