Once fields have served their purpose currently the only way to keep them but not show them to members is to make them Internal use fields. But this may make the administrative UI cluttered if there are many fields. Deleting these "archived" fields and the underlying data is the only option.

It would be nice if these fields could be "hidden" or archived for future access but only once "unarchived". Similar functionality as for contact archiving but for attributes of a contact or member.