Quiz

You can't do that without hacking the code (or your theme).

In your theme, you should be able to add a style rule something like

.que .info .grade { display: none; }

(You may need to use firebug to get that exactly right.) Alternatively, in mod/quiz/locallib.php, find the line that says

        $options->marks = self::extract($quiz->reviewmarks, $when,
                self::MARK_AND_MAX, self::MAX_ONLY);

and replace MAX_ONLY with HIDDEN.