I was able to delete it in Schoology, and change the assignments to (ungraded). However, I can not see how I can delete it in eSchool+.
Thank you for posting in the PowerSchool Community for assistance!
If the category has not been used, then you can delete the category if you are on the grade book by navigating to the categories page and you should be able to see a checkbox under the trash can icon. Click on the checkbox and click save.
If the category has been used, then all usages of it need to be found.