If it's my archiving plugin, it doesn't delete any files by itself.. instead it deletes the ticket via normal osTicket semantics, so if it has an attachment, it's up to osTicket to delete the files.
If you dig into their code, you'll see that it doesn't initiate an attachment deletion straight away either:
https://github.com/osTicket/osTicket/blob/develop/include/class.ticket.php#L2697
Relying instead on cron to purge the files "randomly".. so, if you don't have cron running, it won't work.
I wasn't happy with that myself, so wrote a script that does it when I wanted:
#!/usr/bin/php
<?php
// Ensure we are in CLI mode
if(php_sapi_name() !== 'cli'){
die("Invalid.");
}
require_once 'main.inc.php';
require_once INCLUDE_DIR . 'class.file.php';
try{
AttachmentFile::deleteOrphans();
}catch(IOException $e){
echo $e->getMessage() . "\n";
}
This forces osTicket to find/delete the attachments, whether in db or filesystem.
YMMV.