Why do certain posts in the classroom list their author as University Administration, and can they be removed?

The original author of the post has been removed from the class. When a student is dropped from a class by having the class removed from their schedule, they are then removed from the class roster. Their posts, however, remain a part of the classroom and cannot be removed.

Note: Instructor's may experience this when their permissions have been removed while the course build and syllabus are publishing.

There is no additional information.