There is no option to delete a candidate. Instead, Reject candidates you're not interested in.
You can then use the filtered views at the top of the candidates table to see only New, Liked, Rejected, or any specific status from the Others menu.
Why can't I delete a candidate?
If you delete a candidate, our system would no longer have any record of their application and our duplicate-candidate detection won't work. We filter out subsequent applications from a candidate who has already applied to your job so you don't see duplicates.