accidently recorded three audio inputs in open broadcaster studios

I can't make out from the descriptions of how the software workds whether a single file per source is created, or just a single file containing a mix of all the sources. In the first case, it's easy - you just ignore the files you don't want. In the second case, there's nothing at all you can do to separate the sources, so you're stuck with what you've got, I'm afraid.