In Exams Organiser go to Tools>Delete Marksheets
Select your criteria from the left hand panel by putting a tick in the required selection, (Season is usually the most relevant)
Click on Refresh
The left hand panel will be populated with all the Marsheets related to your previous selection.
In the right hand panel select the Marksheets you wish to Delete
Click on the Delete button at the bottom left of the window.
You must be aware that this only deletes the Marksheet and not any entries that have been made in the Marksheet eg. If you have entered students for an exam and then delete the Marksheet the student will still be entered for the Exam, if the Entries have been made in error they will need to be removed before deleting the Marksheet.
If a Marksheet is deleted and Entries need to be removed, you will have to recreate the Marksheet to send an amendment file to the board.