In windows it is in a folder called appdata, you can go directly by pressing Win+R and typing %appdata%, hit run and look for the paper lily folder, then simply delete the files in the save folder.
I wrote this using translator so sorry if you can't understand it.
Idk, if it is in the appdata folder it is most likely a save or configuration file, you can delete the entire PaperLily folder if you want, it will be recreated the next time you open the game.
The save files are the .sav files and are usually called "slot1" "slot2"
