I work with Ghost.
I currently have a problem with the “portal-configuration”. In the Ghost Admin configs you can easily turn the newsletter and all the features to it off. But even after I turned it off, you can subscribe and unsubcribe in the portal, which can get confusing, cause there is nothing you can subscribe to.
Newsletters and membership are related but independent features in Ghost. If you want to disable signups altogether, go to Settings → Membership. Set the Subscription access option to Nobody.
So just for my understanding.
The Sign Up or Subscribe Button is there to Subscribe to the Newsletter only?
So people who Sign In to the site only do that for the Newsletter?
I believe those buttons also cause you to become a “member”, but I’m not aware that there’s anything interesting for members to do besides potentially pay a membership fee.
If the buttons don’t disappear from your theme when the newsletters are disabled, you may need to adapt your theme.