How to process Hired candidate changed mind; wants 2nd job?

Summary:

Is there a best practice to be used in the following situation:

We have a candidate that is in HR processed status but they have decided they no longer want the job they have been hired on; instead they want to be hired to a different job/req. (The Start Date on the new job is a few days earlier (3/27) than the job in HR Processed status (4/1).)

We seem to struggling with two issues: 

1)     How to ‘release’ the person from HR Processed record and then hire them on the new req with the correct Worker status as the system appears to be only allowing only a ‘Transfer’ option instead of ‘Add Pending Worker’ on the new requisition.