Why can't I delete a student from a class?

There are two reasons you may not be able to delete a student from a class:

If the class is controlled by Clever, students cannot be deleted from it manually. All removals of students are done by automated Clever syncing.
If the class is not controlled by Clever and you cannot delete a student from it, it is because you are a secondary teacher for the class. Only primary teachers (class owners) can delete students from a class.

Secondary teachers cannot delete students from a class, archive or delete a class, or delete class assignments.