Can't you go into the data folders (I think it's data/misc) and delete it from there? It should come up as something like ^1[JIM_BOB.ply" if your username was JIM_BOB. At least that's what it's like on my PC, but my PC is strange.
I'm not sure, wait for some approval by a clever person, incase it blows up your system.
Hope it helps,