Removing attachments is no rudimental step because of the way Zammads attachments work.
If you receive two mails with an identical attachment, Zammad will only save the attachment once and cross reference it to the other article if needed.
Now in such a situation, if you happen to have such a situation with tickets where one is farily old and the other one fairly new, you can’t really decide on how to act in that situation.
I mean, yes you can, but this adds further layers of complexity we usually try to avoid.
There’s no easy way in Zammad and while technically possible with rails commands, we would never suggest doing that move.
That being said, this proberbly won’t meet our 80% user base rule at the moment.
Howevert, I do understand your requirement. I’m afraid right now it’s rather a edge case in Zammads universe. 