Here's how to remove a Chatterbox comment you made on another member's page:
1. Click on your name, on the gray navigation bar at the top of your page.
2. Scroll down to your Chatterbox widget.
3. Click the 'See All' link at the bottom of your chatterbox.
4. That will take you to another page that lists all of your Chatterbox comments.
5. Find the members chatterbox you left the comment on.
6. Click the 'View Chatter with' link under the members name
7. Delete the comment you'd like to remove.