deleting single email from "conversation" view
 

This may perhaps belong in the Gmail forum, or the technical forum, but I reckoned I'd try it here.

I sent a text file to an online acquaintance who had expressed interest in it, which in due course it turned out he did not have. As it is proprietary material, I don't want unwanted or unneeded copies of it floating around, so I asked him please to delete it, but then I realized that (aside from the unavoidabble fact that nothing is ever truly deleted, which one simply has to live with) this isn't as simple as it sounds. There's his webmail Inbox, but what if his provider uses conversation view? Every time he replies to me regarding the matter, there the document is, dutifully sitting in the lengthening thread. It's not just a matter of his deleting it from an Inbox and/or perhaps a folder.

Is there any way for him to delete it from his online email short of deleting the entire "conversation," including perhaps some parts that he might wish to retain?

As for deleting it locally, depending on whether he downloaded it and if so, how he handled it locally, it may reside on his hard drive as a separate WP file, or in his mail client if he uses one, and so on. I must depend on his tech savvy (probably nonexistent) to realize this and delete it from what may be several different iterations.

But mainly, my question is how to delete something like that from, say, a Gmail account with "conversation" view? Is there any way he can do it that I could explain to him, short of some unacceptably broad "nuclear option"?

Thanks for whatever advice anyone can provide.

Not 100% sure if this will work, but try turning off conversation view in settings. Then go to your Sent folder and delete the offending email. Probably you should also then empty the Trash folder. Now turn back on conversation view. Do you still see the offending email?