I just figured out how to delete all presets in FxSound, including the factory ones
Just delete the files in these two folders:
C:\Users[User Name]\AppData\Roaming\FxSound\Presets
C:\Program Files\FxSound LLC\FxSound\Factsoft
Be careful not to delete something important by accident.
You can even replace the factory presets with your own and have literally (zero presets ) if you want.
Sharing this here because I searched everywhere and couldn’t find anything — had to figure it out manually.
Hope this helps!