Visual Basic.NET - Convertir fecha tipo texto

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

    Dim FechaHora As String

    Dim Fecha As String

    Dim Hora As String

    FechaHora = TBFechaHora.Text

    CambiarFechaHora(FechaHora, Fecha, Hora)

    TBFecha.Text = Fecha

    TBHora.Text = Hora

End Sub

Private Sub CambiarFechaHora(ByVal FechaHoraInicales As String, ByRef FechaTratada As String, ByRef HoraTratada As String)

    Dim Fecha As String

    Dim Hora As String

    Dim Mese As String

    Dim Dia As String

    Dim Ano As String

    Dim Hor As String

    Dim Minu As String

    Dim Seg As String

    Dim SepFecha As Integer

    Dim SepHora As Integer

    Dim SepFechaHora As Integer

    ' Separar Fecha y Hora

    SepFechaHora = FechaHoraInicales.IndexOf(" ")

    Fecha = FechaHoraInicales.Substring(0, SepFechaHora)

    Hora = FechaHoraInicales.Substring(SepFechaHora + 1)

    ' Tratar Fecha

    SepFecha = Fecha.IndexOf("-")   ' Cambiar - en / segun el caracter utilizado, tambien en las lineas siguiente

    Ano = String.Format("{0:0000}", CType(Fecha.Substring(0, SepFecha), Integer))

    Mese = String.Format("{0:00}", CType(Fecha.Substring(SepFecha + 1, Fecha.LastIndexOf("-") - SepFecha - 1), Integer))

    Dia = String.Format("{0:00}", CType(Fecha.Substring(Fecha.LastIndexOf("-") + 1, 2), Integer))

    FechaTratada = Dia & "-" & Mese & "-" & Ano  ' Utilizar el caractere que gustamos

    ' Tratar Hora

    SepHora = Hora.IndexOf(":")

    Hor = String.Format("{0:00}", CType(Hora.Substring(0, SepHora), Integer))

    Minu = String.Format("{0:00}", CType(Hora.Substring(SepHora + 1, Hora.LastIndexOf(":") - SepHora - 1), Integer))

    Seg = String.Format("{0:00}", CType(Hora.Substring(Hora.LastIndexOf(":") + 1, 2), Integer))

    HoraTratada = Hor & ":" & Minu & ":" & Seg  ' Escribir como gustamos, por ejemplo : HoraTratada = Hor & "H" & Minu & "'" & Seg & "''"

End Sub

Private Sub q(sender As Object, e As EventArgs) Handles ComboBox1.SelectedIndexChanged

    'Aqui recorro el datagridview y agrego en cada fila el valor del combobox

    For i = 0 To ConfigurableDataGridView.Rows.Count - 1

        ConfigurableDataGridView.Rows(i).Cells("Codigo").Value = ComboBox1.Text

    Next

For i = 0 To ConfigurableDataGridView.Rows.Count - 1

        ConfigurableDataGridView.Rows(i).Cells("Hora").Value = ConfigurableDataGridView.Rows(i).Cells("DateTimeDataGridViewTextBoxColumn").Value

    Next

End Sub

Private Sub BackgroundWorker1_DoWork(sender As Object, e As System.ComponentModel.DoWorkEventArgs) Handles BackgroundWorker1.DoWork

    Try

        Dim i As Integer

        For i = 1 To 1000

            BackgroundWorker1.ReportProgress(i / 10)

            Threading.Thread.Sleep(10)

        Next

        Dim columnas As Integer = ConfigurableDataGridView.ColumnCount

        Dim filas As Integer = ConfigurableDataGridView.RowCount

        Dim c, f As Integer

        Dim Columna As String()

        ReDim Columna(0 To columnas - 1)

        For f = filas To 1 + 1 Step -1

            For c = 0 To columnas - 1

                Dim valor As String = ConfigurableDataGridView.Rows(ConfigurableDataGridView.Rows.Count - f).Cells(c).Value.ToString()

                Columna(c) = valor

            Next

            Dim resultado As String = HistoricosTableAdapter.ScalarQuery(Columna(1), Columna(2), Columna(3), Columna(4), Columna(5), Columna(6), Columna(7), Columna(8), Columna(9), Columna(10), Columna(11), Columna(12), Columna(13))

            If resultado = Nothing Then

                HistoricosTableAdapter.Insert(Columna(0), Columna(1), Columna(2), Columna(3), Columna(4), Columna(5), Columna(6), Columna(7), Columna(8), Columna(9), Columna(10), Columna(11), Columna(12), Columna(13))

            Else

                HistoricosTableAdapter.UpdateQuery(Columna(0), Columna(1), Columna(2), Columna(3), Columna(4), Columna(5), Columna(6), Columna(7), Columna(8), Columna(9), Columna(10), Columna(11), Columna(12), Columna(13))

            End If

        Next

        e.Result = Me.HistoricosTableAdapter.Fill(Me.NulecDataSet.Historicos)

    Catch ex As System.Exception

        MsgBox("Los datos ya existen, o la columna código está vacía")

    End Try

End Sub