You can block any applicant if you don't want to see them in your talent pool.
To block applicants you need to:
Open Candidate profile
Choose the Block button from the right part of the screen
Click Submit
After blocking a candidate you won't be able to see any other applications from this candidate. You can Unblock the same candidate any time you want. Simply do these steps:
From Candidates choose Blocked Applicants
Open Candidate profile
Choose the Unblock button from the right part of the screen
Click Submit