This seems like a really silly question but I can't find an option in game to erase save files? Anyone know a quick way to do it?

Hmm...I have the Nintendo Switch version and it doesn't even have save files. It just has the one file and that's it, so to delete it I'd just delete my save data for the game from the Switch itself. I don't know what platform you're using so I'm not sure I can help.