My understanding is that you can't delete the old uploaded resumes. If I were you I would include the date in the file name (02SEP2014 J.Doe Resume), so you can ensure HR is selecting the correct resume to review. And someone else might have tried this and can comment, but it might be possible to upload your current resume multiple times and kick out the old resumes (if it only keeps the 3 or 5 most recent uploads).