When you say you "couldn't" unsubsribe, please provide more details that will help us find, duplicate, and hopefully resolve the problem:
• Did you receive any error messages? if yes, what were they (please copy and paste the entire message, screenshots are best)?
• What were the exact steps you took before having the problem? Please be as specific as possible so we can do exactly what you did.
• Which browser and version are you using (eg., Firefox 3.5.9, Internet Explorer 7, etc.)
• Have you logged out, deleted your internet cache, logged back in, and tried again?
• Have you tried a different browser?
Once you unsubscribe from an item you should definitely not receive emails any more. Unsubscribing is a pretty easy process:
https://www.backyardchickens.com/a/subscription-tutorial (specifically the "Edit Your Subscriptions" section)