I'm clumsy dummy so I've gotta ask before I make mistake, what exactly are the files I need to delete?
RenPy games have two separate persistent files. The first file is simply found in the folder you dowloaded under „game\saves“ and is called „persistent“.
The other one is under „C:\Users\user\AppData\Roaming\RenPy“ Just select the RenPy folder, find the „DatingSim389“ folder inside of it, and delete the persistent file that one has as well.
That should take care of everything :)