I've a list with an attachments column and I need to delete only certain files from the item list. I been looking in to the forums and saw a http webserver use but I'm getting errors with the url.
I was looking for guidance on a similar thing - in my case, delete all attachments on a given list item. I found this video which you may find useful: https://www.youtube.com/watch?v=sCjNbvzjVjw
Just FYI, the video includes specific steps and configuration for an O365 list WF. Unfortunately it didn't work for me, but it looks like that's due to authentication or permissions rather than the WF being at fault.