Dataset สามารถเคลียร์ค่าได้ไหมครับ มีวิธีการอย่างไรบ้างครับ

sub SetGrid()
Datagridview.Datasource =null
ds = BindDS()
   With DataGridView1
       .DataSource = ds.Tables("TableName")
       .AutoGenerateColumns = False
   End With
end sub

Private Sub showDatagridview1()

        conn.Open()
        cm = conn.CreateCommand()
        With cm
            .CommandText = "SELECT * FROM GoodsExport ORDER BY rec_no"
            .CommandType = CommandType.Text
        End With
        da = New SqlDataAdapter(cm)
        da.Fill(dt)
        conn.Close()

        DataGridView1.DataSource = dt
        DataGridView1.Columns.Clear()

        Dim col As DataGridViewTextBoxColumn

        col = New DataGridViewTextBoxColumn()
        With col
            .DataPropertyName = "rec_no"
            .HeaderText = "  ลำดับ"
            .Width = "100"
        End With
        DataGridView1.Columns.Add(col)

        col = New DataGridViewTextBoxColumn()
        With col
            .DataPropertyName = "dates"
            .HeaderText = "  วันที่จำหน่าย"
            .Width = "150"
        End With
        DataGridView1.Columns.Add(col)

        col = New DataGridViewTextBoxColumn()
        With col
            .DataPropertyName = "goodsID"
            .HeaderText = "  รหัสครุภัณฑ์"
            .Width = "150"
        End With
        DataGridView1.Columns.Add(col)

        col = New DataGridViewTextBoxColumn()
        With col
            .DataPropertyName = "goodsName"
            .HeaderText = "  ชื่อ"
            .Width = "150"
        End With
        DataGridView1.Columns.Add(col)

        col = New DataGridViewTextBoxColumn()
        With col
            .DataPropertyName = "barcode"
            .HeaderText = "   บาร์โค้ด"
            .Width = "150"
        End With
        DataGridView1.Columns.Add(col)

        col = New DataGridViewTextBoxColumn()
        With col
            .DataPropertyName = "goodsModel"
            .HeaderText = "  ยี่ห้อ/รุ่น"
            .Width = "150"
        End With
        DataGridView1.Columns.Add(col)

        col = New DataGridViewTextBoxColumn()
        With col
            .DataPropertyName = "goodsDetail"
            .HeaderText = "  รายละเอียด"
            .Width = "150"
        End With
        DataGridView1.Columns.Add(col)

        col = New DataGridViewTextBoxColumn()
        With col
            .DataPropertyName = "room"
            .HeaderText = "  ห้อง"
            .Width = "150"
        End With
        DataGridView1.Columns.Add(col)

        col = New DataGridViewTextBoxColumn()
        With col
            .DataPropertyName = "amountExport"
            .HeaderText = "  จำนวนจำหน่าย"
            .Width = "150"
        End With
        DataGridView1.Columns.Add(col)


    End Sub  'โชว์ข้อมูลใน Datagridview1

 If MessageBox.Show("กลับหน้าหลัก ใช่หรือไม่ ?", "Message", MessageBoxButtons.YesNo, MessageBoxIcon.Question, MessageBoxDefaultButton.Button1) = Windows.Forms.DialogResult.Yes Then
            DataGridView1.DataSource.Clear()
            Me.Close()
        End If

    ds = BindDataExport()
        With DataGridView1
            .DataSource = ds.Tables("GoodsExport")
            .AutoGenerateColumns = False
        End With

Private Sub Form2_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        DataGridView1.DataSource = Getdata("SELECT * FROM dbo.Company_Position", "Data Source=192.168.6.204,1433;Initial Catalog=BASE;User ID=LAMAKA.TOR;Password=*******").DefaultView()

    End Sub
    Function Getdata(sql As String, connstring As String) As DataTable
        Dim ds As System.Data.DataSet = New DataSet()
        Dim adapter As SqlClient.SqlDataAdapter = New SqlClient.SqlDataAdapter(sql, connstring)
        adapter.Fill(ds)
        Return ds.Tables(0)
    End Function