(1) Click on the author's name at the top of the article
(2) It will take you to the author's profile page. There, at the top right, click on the "Mute" button.
Result: You won't see articles by that author or receive email alerts for articles by them.
Free users currently have 3 mutes, paying subscribers unlimited Mutes.
Want to give Seeking Alpha Premium a try? You can sign up from here.
Customer support service by UserEcho