Here’s a common Unsubscribe footer link, complete with merge codes, to be used if you embed it directly into the HTML source code of your template.
Intended for: [email] <a href="[unsubscribe, https://www.InsertYourDomainHere.com/unsubscribed]">Unsubscribe</a>
Once you create a successful Unsubscribe link on your email template you need to make sure that actual URL/page exists on your website. Build a page on your site that has appropriate Unsubscribe language (e.g. You have successfully unsubscribed), the URL would be www.InsertYourDomainHere.com/unsubscribed.