Modules in elective areas that were selected in the past but will no longer be taken can be cancelled as long as no examination (failed attempt) has been made. You can only cancel the module independently during the registration semester, after which you please to have a cancellation carried out. contact the Office for Student Affairs
Unused module registrations block the further selection of modules, so it is advisable to have the registrations corrected. A notification of sickness is not a booking in the above sense and you can cancel the module through the Office for Student Affairs.