Only moderators can adjust this setting. Here’s how:

1. From the list on the left, click Management.
2. Under "Group Settings", click on Description & Appearance link.
3. In the "Description" section, click Edit.
4. Scroll down until you see "Listing Type", at the bottom.
5. Select Not listed in Yahoo! Groups directory.
6. Click Save Changes.

Note: If you change your listing status, it may take up to 24 hours for the change to go into effect.