Yes, you may use our member interface to add or remove RespectMyPrivacy service on any domain registered through NearlyFreeSpeech.NET at any time, as long as the registration is not expired and the TLD supports private registrations. The .us TLD is currently the only one we offer that does not support private registrations.
To add it: Visit the Domains panel. Under the "Registrar" column, select "Manage" for the relevant domain. The Registration Info panel for your domain will have an "Add RespectMyPrivacy" action in the "Actions" box.
To remove it: Visit the Domains panel and, under the "Registrar" column, select "Manage" for the relevant domain. The Registration Info panel for your domain will have a "Remove RespectMyPrivacy" action in the "Actions" box.