Очистить DataGridView от значений

    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
        DGW_Clear(dgw1, 24, 25)
    End Sub
    Private Sub DGW_Clear(ByVal dgw As DataGridView, ByVal row As Integer, ByVal col As Integer)
        For i As Integer = 0 To row - 1
            For j As Integer = 0 To col - 1
                dgw1(j, i).Value = ""
            Next j
        Next i
    End Sub

 
    Public Class Form1
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Column1 = New System.Windows.Forms.DataGridViewTextBoxColumn()
        Column2 = New System.Windows.Forms.DataGridViewTextBoxColumn()
        Column3 = New System.Windows.Forms.DataGridViewTextBoxColumn()
        Column4 = New System.Windows.Forms.DataGridViewTextBoxColumn()
        Column5 = New System.Windows.Forms.DataGridViewTextBoxColumn()
        Column6 = New System.Windows.Forms.DataGridViewTextBoxColumn()
        dgw.Columns.AddRange(New System.Windows.Forms.DataGridViewColumn() {Me.Column1, Me.Column2, Me.Column3, Me.Column4, Me.Column5, Me.Column6})
        dgw.RowCount = 6
        For i As Integer = 0 To 5
            For j As Integer = 0 To 5
                dgw(j, i).Value = 12345
            Next
        Next
    End Sub
    Private Sub Button4_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button4.Click
        dgw.Rows.Clear()
    End Sub

        dgw.Rows.Clear()
        dgw.RowCount = 6

Dim intRowsCount as Integer = dgw.Rows.Count
dgw.Rows.Clear()
dgw.RowCount = intRowsCount

    Sub cleaner()
        DS.Clear()
        DataGridView1.Refresh()
    End Sub
 
Private Sub Button4_Click(sender As System.Object, e As System.EventArgs) Handles Button4.Click
        cleaner()
            'А потом снова назначил:
        Dim DS As New DataSet
        DS.ReadXml(Application.StartupPath & "\myxml.xml")
        DataGridView1.DataMember = "Item"
        DataGridView1.DataSource = DS
    End Sub