in locallib.php [568:584]
public function remove(stdClass $submission) {
global $DB;
$fs = get_file_storage();
$fs->delete_area_files($this->assignment->get_context()->id,
'assignsubmission_onenote',
\local_onenote\api\base::ASSIGNSUBMISSION_ONENOTE_FILEAREA,
$submission->id);
$currentsubmission = $this->get_file_submission($submission->id);
if ($currentsubmission) {
$currentsubmission->numfiles = 0;
$DB->update_record('assignsubmission_onenote', $currentsubmission);
}
return true;
}