If it's just surface rust you should be able to get it off with a bit of steel wool or a wire brush... if it's actually rusting away I don't think you'll have much hope...

If all else fails I'd just go down to bunnings or something and get some spray paint and spray paint over the top of it ><;; Just give it a wipe down/clean off first so you don't have any bitty bits flaking off...

GL! xx