code: @SuppressWarnings("unused") // called through reflection by RequestServer
    public FramesV3 delete(int version, FramesV3 frames) {
      Frame frame = getFromDKV("key", frames.frame_id.key()); // safe
      frame.delete();             // lock & remove
      return frames;
    }
docs: Remove an unlocked frame.  Fails if frame is in-use.