Close current form and open new one of that form closed

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C#

forms

C#5.0

i have 2 form in form 1 i have a button when i click on button form 2 will be show and my data are showing on form 2 so far its OK but i want when one of form 2 its open if user click on button in form 1 then close this form 2 and open a new one! not open an other form 2 i hope u understand my question :D sorry for bad English

and here is button code :

    private void btnSave_Click(object sender, EventArgs e)
    {

            if (RadioMale.Checked == true)
            {
                jensiyat = "مرد";
            }
            else { jensiyat = "زن"; }
            if (RadioMarried.Checked == true)
                tahol = "متاهل";
            else tahol = "مجرد";
        Class1.txt +=
           "________________________\n\n" + "مشخصات مربوط به  خانم/آقای " 
           + tbFamily.Text + "\n________________________" +
            "\nنام و نام خانوادگی: " + tbName.Text + " " +
            tbFamily.Text + "\n" + "ایمیل: " + tbEmail.Text + "\n" + "شماره ملی: " +
            tbCodmeli.Text + "\n" + "سریال شناسنامه: " +
            tbSerialShenasname.Text
            + "\nشهر محل زندگی: "+ shahr + " - " + TreeShahr.SelectedNode.Text
            + "\nآدرس: " + tbAddress.Text + "\n"
            + " تحصیلات : " + ComboTahsilat.SelectedItem
            + "\nجنسیت : " +jensiyat
            + "\nوضعیت تاهل: " + tahol
            + "\nتاریخ تولد: " + BirthTimePicker.Value.ToPeString()
            + "\n__________________________________________________";

        Form frm2 = new Form2();
        frm2.Show();
    }

What I have tried:

i tried form instance function but its not working its just hold this form 2 and will not allow to open new one! with these code:

public static Form2 Instance
   {
       get
       {
           if (_form2 == null)
           {
               _form2 = new Form2();
           }
           return _form2;

       }
   }