Deletes a rubric. The requesting user and course owner must have rubrics creation capabilities. For details, see licensing requirements. This request must be made by the Google Cloud console of the OAuth client ID used to create the corresponding rubric. This method returns the following error codes: * PERMISSION_DENIED if the requesting developer project didn't create the corresponding rubric, or if the requesting user isn't permitted to delete the requested rubric. * NOT_FOUND if no rubric exists with the requested ID or the user does not have access to the course, course work, or rubric. * INVALID_ARGUMENT if grading has already started on the rubric.