The differences among the words archived, filed, and shelved seem to me a matter of degree and associated with information, a project, or something similar. If something is "filed," then you can still retrieve it. "Archived" is filed, but may not be as easily retrieved--that is, it may be stored in another format (compressed data, for instance) or, if hard copy, may be in a warehouse somewhere. "Shelved" in the movie industry used to be used to refer to a project that had been abandoned and put on hold indefinitely, not likely to be recovered.
Since you're coding and using language to refer to a date of an event that has passed, I think "shelved" comes closest.