2 Ways. Easiest is when making a new character to juts save over ALL previous saves.
Other, Better option is to find your game folder, and in the game folder of your game folder (I.E. MonGirlDreams-Alpha-v26.1a-pc -> game -> saves) and there is a save folder in that directory. Delete the auto, quick and numbered files. If it doesn't launch afterwards, uninstall and reinstall (At least as far as I know)