[vcloud_director] fix typo as per #2621
[Brightbox] Remove old #destroy request

All the "destroy" methods were renamed to "delete" but this file was not
removed.
Merge pull request #2622 from alphagov/2621_fix_typo

[vcloud_director] fix typo as per #2621
Merge pull request #2623 from brightbox/remove_old_destroy_request

[Brightbox] Remove old #destroy request