请参考这个答案

以编程方式关闭代码后面的aspx页面 [ ^ ]

Please refer to this answer
Programmatically close aspx page from code behind[^]

Protected Sub Page_LoadComplete(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.LoadComplete

      
       Me.closebutton.Attributes.Add("onclick", "javascript: window.close();")

   End Sub