Here is the error to begin with.
As you can see above, I cannot simply delete the job straight away (this is still a bug as of the date of this post), so what I need to do is create an LCM export for that job, modify the xml file, and re-import the file again.
1. Export the LCM job definition
3.Edit the XML file and change the end dates to a past date
This is the original XML file
This is the modified XML file
In snippet format
4. Finally, import the updated LCM file
Once the file is imported, you will see the updated "Repeats" and "Scheduled End Time" for the scheduled job.
Depending on whether you have selected an end date in the past, or not, the job will be updated to reflect the new end date and once it passes that date, the job will be completely removed from the scheduler.