Blocking someone from receiving emails
You sure can prevent someone from receiving your emails, without relying on them to unsubscribe themselves!
In the Subscribers area, search for the contact email using the search bar at the top of your page. Hover over the contact and on the right hand side you'll see a suppress
To suppress many contacts at once, use this guide.
Related Topics:
Excluding an Entire List from Just a Mailing
How People Unsubscribe from Emails
More About the Suppressed List