Close iframe from another page after submit code behind

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C#

ASP.NET

IFrame

I have an a web application which have a button that will open an iframe form windows.

open.aspx is the button click

supervisor.aspx is the page open using iframe

the open.aspx

<div style="vertical-align: middle; text-align: center; left: 500px; width: 122px; position: absolute;  top: 560px; height: 50px; z-index: 126; right: 889px; font-size: 50pt; font-family: Calibri; font-weight: bold;" id="uncheckbutton">
    <asp:ScriptManager ID="ScriptManager1" runat="server">  
</asp:ScriptManager>  
      <asp:Button ID="Button1" runat="server" Text="UNCHECK" />
//this is the onclick button to open the iframe
    

<cc1:ModalPopupExtender ID="mp1" runat="server" PopupControlID="Panl1" TargetControlID="Button1"  
    CancelControlID="Button2" BackgroundCssClass="Background">  
</cc1:ModalPopupExtender> 

        

  <asp:Panel ID="Panl1" runat="server" CssClass="Popup" align="center" style = "display:none">  
    <iframe style=" width:400px; height: 150px;" id="irm1" src="Uncheck popup.aspx"  runat="server"> </iframe> 
         <asp:button Top="100px" id="button2" runat="server" text="CLOSE"  />  
</asp:Panel>  

and this is the supervisor.aspx(the iframe)

<asp:TextBox ID="inputid" runat="server" Font-Size="14px" ></asp:TextBox>  

<asp:Button ID="Button3" runat="server" Text="Uncheck"  OnClick="btnCheck_Click"  /> 

if the user enter the correct username, i want the iframe to automatically close.

this is my supervisor.aspx.cs

  protected void btnCheck_Click(object sender,EventArgs e)
        {
          
            string uncheck = inputid.Text;                                                                        
           
            bool supervisor = Cls.GetUncheckSupervisor(uncheck);
          
            

            if (supervisor==true)
            {
                this.ClientScript.RegisterClientScriptBlock(this.GetType(), "Close", "window.close()",

.true);

            }
            else
            {
               

                Show("Wrong ID!");

            }

if the supervisor is true, how can I automatically closed the iframe? for now I use a button click to close and I want to avoid less clicking.


Thanks in advance

What I have tried:

I have try using javascript but the iframe still won't close although the function works.
I following this link
https://stackoverflow.com/questions/43527062/how-to-close-window-after-iframe-form-submits and also https://stackoverflow.com/questions/29258881/close-iframe-from-another-webpage-asp-net