A Follow is the option to receive an e-mail notification as soon as the followed streamer begins their broadcast. You can unfollow someone at any time. Just go to your connections (https://picarto.tv/settings/connections) and click on the one you want to unfollow. An unfollow button will appear and once you click it you've successfully unfollowed the person.
If you follow someone the followed streamer gets a notification right away telling them who is following.