If you are trying to inactivate a course, you need to ensure that no sections exist in the effective term or later. If sections exist, you or your unit scheduler will need to login to CLSS and select the term under the "Future" heading. Find the course and click the red x next to the sections that exist. If the red x is not available, then the course cannot be deleted and you will need to select a later effective term. Once the schedule has been published, courses can only be cancelled, not deleted.
If you have questions about how to delete a course, please see your unit scheduler.