Close IFrame form another page

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ASP.NET

Hi,

On Button click event I am calling another page through IFrame.

 function ShowIFrame() {
            var modal = $find("newtest");
            $("#dialog").empty();
            $("#dialog").append("<iframe frameborder='0' sandbox='allow-top-navigation' target='_Parent' seamless='seamless' width='100%' height='100%' src='ForgetPassword.aspx'></iframe>");
            modal.show();
}

On button click event in the calling page(ForgetPassword.aspx) I want to close the above IFrame.
I have tried this.

ScriptManager.RegisterClientScriptBlock(this, GetType(), "Authentication Type", "javascript:function(){window.parent.document.getElementById('dialog').visible = false;}", true);

But it's not working for me. Please help.
Thanks in advance