Putting it out there can get you into trouble. Not only is there "publisher's remorse" but also the more serious take-down notice that may crash into your client's inbox from time to time claiming that the content of their web page has infringed one of the sender's rights. It's easy enough if the client owns the site to eliminate the offending material or whole pages; that's why delete buttons were made. But Google is not so easily deterred. Having indexed material it may continue to serve up links to that material, if only in its cache; and its bots may continue to worm their way into material that the client thought had been successfully hidden.
What to do? Google's not exactly the corner store, where you can drop in and have a decent chat with the owner, and on their sites you'll notice a distinct lack of email addresses or phone numbers you can use to send them your problems.
Google knows it's a juggernaut (fun etymology in this case: "lord of the universe"). And eventually it provides.
Google's Webmaster Central Blog has released the first in a series of entries showing us how to pull our coals out of the fire: "URL removal explained, Part I: URLs & directories." I'm not going to try to reproduce their instructions here: it's not an occasion for approximation. But I can say that getting them to remove a URL involves essentially two steps: blocking their bots correctly, and then submitting the URL to their removal tool.
And because we sometimes make mistake upon mistake — or, more happily, you were able to defeat the take down notice — the client can undo the removal and re-instate the URL.