To achieve the same, add the CEWP to the page, where you do not want to display the Quick Launch. Open Source Editor of CEWP and add the following
<style>
.ms-quicklaunch
{
display:none;
}
.ms-navframe
{
display: none;
}
</style>
Once the above <style> has been added, go to Advance Setting, set “Audience Targeting”. Set the group/audience to which you do not want to display the Quick Launch bar.
I have set the “Visitors” group in Audience Targeting. This setting will not allow the “Visitors” to see the Quick Launch bar.
I have a moss_user1 in Visitors Group and moss_user2 in Members Group.