Delete Data in Grid View

Imports System.Data
Imports System.Data.SqlClient
Imports System.IO
Partial Class admin_student
    Inherits System.Web.UI.Page
    Public cn As SqlConnection
    Public da As SqlDataAdapter


  Public Function fillgrid()
        cn = New SqlConnection("Data Source=;Initial Catalog=;User ID=;Password=")
        da = New SqlDataAdapter("select * from s_reg", cn)
        ds = New DataSet()
        da.Fill(ds)
        GridView1.DataSource = ds
        GridView1.DataBind()
    End Function
    Protected Sub GridView1_RowDeleting(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.GridViewDeleteEventArgs) Handles GridView1.RowDeleting
        cn = New SqlConnection("Data Source=;Initial Catalog=;User ID=;Password=")
        da = New SqlDataAdapter("select * from  s_reg", cn)
        Dim cmd As SqlCommandBuilder = New SqlCommandBuilder(da)
        ds = New DataSet
        da.Fill(ds)
        ds.Tables(0).Rows(e.RowIndex).Delete()
        da.Update(ds)
        GridView1.DataSource = ds
        GridView1.DataBind()
    End Sub