Dim i&, ii&

        For i = 0 To DataGridView4.Rows.Count - 2


            For ii = i + 1 To DataGridView4.RowCount - 2


                If DataGridView4.Rows(i).Cells(0).Value.ToString() = DataGridView4.Rows(ii).Cells(0).Value.ToString() Then

                    '  MsgBox(DataGridView4.Rows(i).Cells(0).Value.ToString())
                    DataGridView4.Rows.Remove(DataGridView4.Rows(i))

                    i -= 1
                End If

            Next

        Next

Public Class Form1
    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        Dim dt As DataTable = New DataTable With {.TableName = "MyTable"}

        dt.Columns.Add(
            New DataColumn With
            {
                .ColumnName = "Identifier",
                .DataType = GetType(Int32),
                .AutoIncrement = True,
                .AutoIncrementSeed = 1,
                .ColumnMapping = MappingType.Hidden
            }
        )

        dt.Columns.Add(
            New DataColumn With
            {
                .ColumnName = "Name",
                .DataType = GetType(String)
            }
        )

        dt.Columns.Add(
            New DataColumn With
            {
                .ColumnName = "Status",
                .DataType = GetType(Boolean),
                .ColumnMapping = MappingType.Hidden
            }
        )

        dt.Rows.Add(New Object() {Nothing, "Karen", False})
        dt.Rows.Add(New Object() {Nothing, "Karen", True})
        dt.Rows.Add(New Object() {Nothing, "Bill", True})
        dt.Rows.Add(New Object() {Nothing, "Karen", False})
        dt.Rows.Add(New Object() {Nothing, "Bill", True})

        DataGridView1.DataSource = dt

    End Sub

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

        Dim dt As DataTable = CType(DataGridView1.DataSource, DataTable)
        '
        ' Find duplicates on Name and Status columns, remember the 
        ' primary key value so we can iterate the DataTable and remove
        ' the duplicates
        '
        Dim duplicates = dt.AsEnumerable().GroupBy(
            Function(r) New With
                        {
                            Key .Name = r("Name"),
                            Key .Status = r("Status"),
                                .Identifier = r("Identifier")
                        }
            ).Where(Function(gr) gr.Count() > 1) _
            .Select(Function(g) g.Key)

        '
        ' Iterate DataTable, get a reference to a duplicate and remove it
        '
        For Each d In duplicates

            dt.Rows.Remove(
                dt.AsEnumerable.Where(
                    Function(r) _
                    r.Field(Of Integer)("Identifier") _
                    .Equals(d.Identifier)).First
            )

        Next
    End Sub
End Class

For i = DataGridView4.Rows.Count - 1 To 1 Step -1
            For ii = i - 1 To 0 Step - 1
                If DataGridView4.Rows(i).Cells(0).Value.ToString() = DataGridView4.Rows(ii).Cells(0).Value.ToString() Then

                    '  MsgBox(DataGridView4.Rows(i).Cells(0).Value.ToString())
                    DataGridView4.Rows.Remove(DataGridView4.Rows(ii))

                    i -= 1
                End If

            Next

        Next