Yes. You can re-perm it straight. Completely cover your head in perm solution and then comb it....get it really straight. I would probably comb it for the entire processing time. Rinse it out and neutralize it. Probably would be best to have a professional do it. It may not get ALL the curl out but you would have some nice body and could get some good volume when blowdrying it.
FOr a less scary route....use Pert Plus. Its cheap shampoo that has perm solution in the mix.