Hi, on the cart version hold SPACE when you boot the game. A menu will appear with an option to reset the hi-score.
I am running it on a floppy. There is a scores.prg. Maybe just delete that file?
yes, delete the file and the game will create a new one with your current score
Where can I download the cart version? There is no such file in the download page. I read elsewhere that this version is slightly improved as well.