If users no longer require a Job Category, the category should be made inactive, not deleted.
However, you cannot do this for the default category. This is set under: Administration > System Initialization > Eralis Job > Job Defaults tab.
You can make the category inactive by going to Administration > Setup > Eralis Job > Job Attributes > Job Category.
If you try and make the category inactive and it is assigned to jobs that are still active, you will get a message saying that the Job Category is still assigned to active jobs and will remain visible until all jobs are no longer active. You won’t be able to assign the category to any new jobs.
If you have the category assigned to jobs or subjobs and they are inactive, then the category will disappear from the My Jobs screen.