Stop sharing a rubric
From EdTech Help
Go to the Rubrics tool
Select the Rubrics tool from the Tool Menu of your site.
Select the Revoke sharing icon [Revoke sharing] for the rubric you would like to stop sharing
Note: You may only revoke sharing for rubrics that have been shared from within the current site. If the rubric had another site of origin, you must go to that site to revoke sharing.