Making amendments once planning permission has been granted usually requires a further new application. However some minor amendments may be achieved by submitting a non-material amendment application.
What does 'non material' mean? Insignificant ie it should have no discernible impact on the development. Whether or not a proposed amendment is non-material will depend on the circumstances of the case – a change which may be non-material in one case could be material in another. If in doubt we recommend you discuss it with the case officer who dealt with the original planning application.