Illnesses can be edited and/or deleted via the table of illnesses.
Navigate to your Illnesses list:
Under the actions column you will see a pencil icon (edit) and trash can icon (delete) depending on the permissions of your role:
Edit an Illness:
Click on the pencil icon to edit the applicable illness.
This will take you into the illness form:
Edit then ensure you Save the illness once you are finished.
Delete an Illness:
Click on the trash can icon to delete the applicable illness.
You will then be presented with the following warning:
Click 'Yes, Delete' to confirm.