https://steamcommunity.com/app/429300/discussions/0/458605613403306861/
This community page on steam helps reset your save data if anyone needs help! You need to delete your persistent save on both your Weathering Feelings game file AND the one in AppData/Renpy file.
SPOILERS
I haven't tested it yet but maybe also just download a new file of the game or restore to get the two previously deleted cloud_demo files again.