Can I remove a script from the build process?

I have some C# files that I’m switching over to a completely new system. I still need the files for reference, and I don’t feel like commenting out their contents. Is there anything I can do in the Editor to keep them out of the build process.

All I can think of is wrapping them in something like “#if 0 … #endif”?

You can do that, or rename them to something like whatever.cs_