I want to start over.
But I don't know how to delete a previously saved game.
Thanks in advance for your help.

I'll answer for myself. The game save is stored in registry keys. I'll give an example on my OS. But your keys may be different.

[HKEY_USERS\S-1-5-21-1329157816-415311311-1331161968-1001\SOFTWARE\Insatiable Game Studio\Loi The Lover]

All you need to delete this registry key location. And save data will be erased.