How do I edit a rubric in a course?
After you've created a rubric, you may need to edit the details in your rubric. Generally you should not edit your rubric if you've already attached it to an assignment that has been published.
Note: If a rubric has been used in an assignment that has received student submissions, or if a rubric is aligned to more than one assignment, you cannot edit the rubric. However, you can create a copy from the assignment rubric.
In Course Navigation, click the Outcomes link.
Click the Rubrics menu  and then click the Manage Rubrics link .
Click the name of the rubric.
Edit Rubric Details
Edit the content of your rubric.
Click the Update Rubric button.