How do I delete all grades/results for one subject?
Make sure that you are using the series that you wish to remove the grades from.
Go to Admin > Edit Subjects
Select the subject to remove grades from on the left and click Delete in the top right.
A prompt will appear asking you to confirm this action as it cannot be undone. It will also inform you that if the subject is in use in other series that these will be unaffected.
Alternatively, you can remove individual grades for a pupil using Admin >Edit Results. Click on a result cell and use the dropdown menu to select the blank value.