You may post a message and then wish to cancel it, either because the message contained incorrect information, or because you regretted what you posted. The best recommended protection against this situation is to first reread anything you write before you post it, and ask yourself if you are sure you want to send it out to the entire world.
Most news readers contain a built-in menu command to cancel a posting.
The cancel message will first be sent to your local news server, which will delete the message from their server right away, and then send the command to all other news servers to which it sent the message in the first place, so that it will be removed at about the same speed that it was posted. However, remember that there is no guarantee that someone won't read your message before it is canceled, especially if the cancel is sent several minutes after the original message. Also, there is no guarantee that it will be canceled before the newsgroup archives pick it up and store it in their database.