django storages aws s3 delete file from model record

You have to explicitly delete the file. You could write a post delete signal or do it in the delete_employee function.

employee.upload.delete(save=False)  # delete file
employee.delete()  # delete model instance

The docs for FileField.delete() explains this.

Note that when a model is deleted, related files are not deleted. If you need to cleanup orphaned files, you’ll need to handle it yourself (for instance, with a custom management command that can be run manually or scheduled to run periodically via e.g. cron).

You should also make sure that there's no other FileField that references the exact same file before deleting it.