delete records

i am using this code to delete recoeds but it only delete record from datagridview i
also want to delete that record from database. plz help

 foreach (DataGridViewRow row in dataGridView1.Rows)
            {
               foreach (DataGridViewRow item in this.dataGridView1.SelectedRows)
     {
         dataGridView1.Rows.RemoveAt(item.Index);
     }