I actually want to know the same thing, it's so irritating when roguelikes don't let you do this

I found my save here:

C:\Program Files (x86)\Steam\steamapps\common\魔王终局\Processes

This was the only folder that stayed on my computer when I uninstalled the game. Deleting the files here and reinstalling reset my game data.

I hope this helps.

Thankyou