Completely reset game? (Steam)

I'm about to play for the first time, but my brother used to use my account and played through all three routes. I want to get the unaltered first time playthrough, but everything I've seen online talks about deleting save files from an "%localappdata%/UNDERTALE" which doesn't exist on my pc. All I have is a "C:\Program Files (x86)\Steam\steamapps\common\Undertale" folder with no discernible save files. Is this basically a fresh copy of the game or do I still have to wipe some files to get a clean slate?