Lots of site owners have disavow files that were made back in the period when Google were throwing out penalties on a regular basis. When we look at many of these files its clear that they often contain lots of sites that perhaps got added in error during the panic of those times.
Many people assume you cant trim these out, there was a recent discussion on Twitter where John Mu of Google clarified that you can indeed edit your disavow files.
So, as part of your stewardship of your link profile, feel free to edit all you like. We would be more than happy to help you do so.