May i ask how to delete columns from datagridview

I am trying write a program to delete my datagridview columns. but my code not effect to delete columns of datagridview.

below is my code. Can someone help me take a look. Did any reference can provide me. thanks a lot  

 For Each c As DataGridViewColumn In DataGridView1.SelectedColumns
            If Not c.IsNewColumns Then
                DataGridView1.Rows.Remove(c)
            End If
        Next