There's no way to adjust the difficulty I'm afraid. It's meant to be difficult at first and then to get easier as you master it.
There's also no way to erase records from inside the game. You could try uninstalling and reinstalling it and see if that clears all the data associated with the app. (If it works it would also erase your current saved game and any achievements.)
I can live with that, thanks.
This turned out to be a little less than straightforward, so for people like me who might be interested in this, the procedure (specific to Mac OS 10.13.6) is:
1) Make sure you quit the game by pressing Command-Q on your keyboard or going to Menu Bar > Beyond the Chiron Gate > Quit. (Clicking the "Quit" button in the game window doesn't suffice; the window disappears, but the application is still running.)
2) Drag the following folders to the Trash:
[name of the startup disk]/Users/[name of your account on your Mac]/Library/"Application Support"/"Beyond the Chiron Gate"
[name of the startup disk]/Users/[name of your account on your Mac]/Library/"Saved Application State"/"com.electron.beyond-the-chiron-gate.savedState"
3) Empty the Trash.
