This is not possible in moodle 1.9 without modifying the code, hiding total course grade hides individual grades too. Here is a workaround :
- In gradebook, turn on editing and go to each student total (can be tedious if having a large number of students enrolled in the course)
- Hide each student total
First screenshot is a student view before hiding, last one is after. VoilĂ :)
References
How to fix it in the code : http://moodle.org/mod/forum/discuss.php?d=175074