Unless you are an administrator or moderator, you can only edit or delete your own messages. You can edit a message (sometimes in a limited time after it is published) by clicking the edit button of the corresponding message. If someone has already replied to the message, a small text will appear at the bottom of the message indicating that it has been edited, the number of times it has been modified, and the date and time of the last edition. . This message will not appear if a moderator or administrator modifies the message, however they can leave a note indicating that they have modified the message on their own initiative. Note that users can not delete a message once someone has responded.