Quoting Paul Johnson, from the post of Wed, 12 Jan:
Is there any facility that can automatically go through the entire system and replace an arbitrary string by regexp? And any way to mass-delete articles by regexp?
none that are integrated into the product itself at the moment but in theory could be written in php.
however, I would consider actions like that dangerous and not allow them through a web interface. if I found myself having to do this, I'd dump the DB first and manipulate a backup first, or the dump (it's plain text) and restore it.