This article explains how you can report a Terms of Service violation and unsubscribe from a  Yahoo! group that you were added to without your permission.

It’s violation of our Terms of Service to add somebody to a group without their permission. If you feel this has happened, please click the Contact Yahoo! link on the lower-right portion of this page and paste one of the messages you receive with the full message headers. Once we receive your information, we will investigate your report and take appropriate action

To leave the group or unsubscribe from the group's mailing lists:

1. Sign into Yahoo! Groups and go to your group on the web.
2. From any page, click Edit Membership at the top of the page.
3. Click Leave Group at the bottom right of this page.
4. Confirm on the next page.

This group will no longer be listed on your My Groups page, and you won’t get any more messages.

To leave/unsubscribe via email:

Send a blank email message to:

[GROUPNAME]-unsubscribe@yahoogroups.com

Make sure to replace "[GROUPNAME]" with the actual name of the group (e.g., pastry_chefs-unsubscribe@yahoogroups.com).