[ANSWERED] How do I add ”[DONE]” in the title of my previous post?

[MinstaKvadrat]

How do I add [DONE] in the title of my previous post?

I was encoraged by a librarian to update the title of an ”add book” post I made by adding [DONE] to its title. I dont know how I can do that? I have the iPhone app.

Also, how do I remove a duplicate post I accidently made?