Candidate Profile vs Pre-Hire

Hi all,

I'm dealing with an urgent recruiting stuff but no experience in Recruiting, so sorry the question might be silly but I can't figure it out with the time pressure. I need to rescind hire, merge the candidate profile to the old terminated worker profile, and then hire again. I rescinded, the candidate appeared at the Job Req, I merged the profiles and now I have no idea how to convert the candidate to the Pre-Hire and start the hire process or let the HRs to start it. Would be so happy if somebody could help here.