how to Unsubscribe From a Newsletter or Mailing List in Gmail
On your computer, go to Gmail. Open an email from the sender you want to unsubscribe from. Next to the sender’s name, click Unsubscribe or Change preferences.
How do I unsubscribe from mailing lists and junk newsletters in Gmail?
On the desktop, Gmail now offers an unsubscribe link at the top of most marketing emails and newsletters. Below the subject line and next to the sender information, there should be an unsubscribe link that will mark the email as spam. After clicking this, Gmail will ask you to confirm your decision.