FIX: Msg 15170, Level 16, This login is the Owner of 2 Job(s). You Must Delete or Reassign these Jobs Before the Login can be Dropped

To resolve the issue, first I need to find which login wizard is trying to drop. Since i didn't know, I have used this aproach:

Find job to login owner relationship:

SELECT j.job_id ,j.owner_sid ,j.name , l.name 
FROM msdb.dbo.sysjobs AS j LEFT JOIN 
sys.server_principals AS l
ON J.Owner_sid = l.sid

Then focus on owners having specific amount (2 in my case) of jobs assinged:

SELECT l.name, COUNT(*)
FROM msdb.dbo.sysjobs AS j LEFT JOIN 
sys.server_principals AS l
ON J.Owner_sid = l.sid
GROUP BY l.name
HAVING COunt(*) = 2 --here you may filter the amount of jobs owner should  own

When I knew the job owner, it was easy to list just his jobs:

SELECT l.name, COUNT(*)
FROM msdb.dbo.sysjobs AS j LEFT JOIN 
sys.server_principals AS l
ON J.Owner_sid = l.sid
GROUP BY l.name
HAVING COunt(*) = 2 --here you may filter the amount of jobs owner should  own

Hope it helps.

With regards, 

Michal.