You cannot edit or delete a marking column calculation after you have associated it with a marking column and class on the Assign Calculations page under Gradebooks. However, you can create a new marking column calculation and change which calculation is assigned to the class then delete the calculation that is no longer in use.

When you assign a different calculation to a class, the grades calculated using the old calculation are retained and the gradebook must be refreshed to update the calculated grades. (BB124143)