1. Go to the Grades tool and Click on Manage Grades:
2. First, you must make sure that the Final Grade column does not effect the total value of the points in your gradebook. Unfortunately when the Final Grade column was created it was done so with a value. So we must first reduce the value so that it doesn't influence your grades. We can't currently make the value zero, but we can lower the column value to .01 of one percent so that it has virtually no effect on the gradebook.
Scroll to the bottom of the page of the Gradebook
A weighted gradebook looks like this:

The Final Letter Grade will have a value as indicated by the red arrows. The value will need to be changed to '0'