Hi David
What version of Moodle are you running? From 1.9.4+ you can select 'My courses' from the
Hide User Fields option setting via
Administration ► Users ► Permissions ► User policies which will prevent those without the 'viewhiddenuserdetails'
permission from viewing these options.
If you're not using this or a later version let me know as we had a previous hack that did the job.
I hope this helps
Cheers
Teresa