If the email lists are Yahoo Groups (eg if the emails are coming from an address like something@yahoogroups.com) then you can log in to your yahoo profile and delete your membership of the groups which you no longer wish to be a member of.
If not and you have tried unsubscribing from the mailing list either by emailing them or from their website but to no avail, then the next time you receive the unwanted email, simply block the sender's email address. In future, you should not get the emails as they will simply get bounced back to the sender, inshaAllah.