Once you post a topic or comment, it not only appears in your online forum, but is also emailed to those group members who have selected to receive forum conversations in their inbox. For this reason, you cannot edit your post once it's up (just like you can't take back an email once sent).
However, if you are a group member and want to take down out-of-date topics or comments, you can either flag a message for a group leader to remove, or contact a group leader directly and ask him/her to remove it. To flag a forum topic or comment:
Click the "flag" checkbox below your post.
Mark the topic erroneous, off-topic, a solicitation, or inflammatory.
The message will be available to a group administrator to moderate. He or she will see that you have flagged the message and can delete the message from the Moderator Tools area.
If you are a group leader or forum moderator, you can remove any forum message at any time by following these directions:
Go to my groups > [group name] > forums.
Find the forum message you want to remove, and click on the title of that message.
Click the "flag" checkbox at the bottom of the message or comment that you wish to remove.
Below the message, a box will appear.
Check "remove this topic" and submit.
Group leaders and moderators can also delete messages that have been flagged by other members on the moderator dashboard. To access this area and see which messages need attention, go to my groups > [group name] > manage and check under the "Moderate Content" heading to see if there are messages for review.