A lot record supports being marked as retained or withdrawn, with a disposition note explaining why. That record is not deleted when this happens — a withdrawn lot keeps its page and states plainly that it was withdrawn, which is the behavior the site is built around: evidence should survive its own bad news, not disappear along with it.
A fuller, published process for how a post-release issue is investigated and communicated beyond the record itself does not yet exist publicly — treat that as an open question rather than an established procedure.