Public Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        For Each row As DataGridViewRow In DataGridView1.Rows
            If row.Cells("Delete").Value = True Then
                DataGridView1.Rows.Remove(row)
             End If
        Next
    End Sub

'...
for each m_row as System.Windows.Forms.DataGridViewRow in me.DataGridView1.Rows
    if m_row.Cells("Column1").Value=true then
        me.DataGridView1.Rows.Remove(m_row)
    end if
next
'...

for (int i = (dgVentaActiva.Rows.Count - 1); i >= 0; i --)
{
    if ((Int32)dgVentaActiva["id_master", i].Value == lVendaElements[idElementVenda].elementIDTemporal)
        dgVentaActiva.Rows.RemoveAt(i);
}
lVendaElements.RemoveAt(idElementVenda);