I earned the Organizer badge without having the required reputation, but re-tagging in the editing section. Later, I saw that I have passed the required rep and granted the re-tagging permission.
Is that possible?
Yes, you can earn in with
So, basically you earn Organizer badge for proper tagging the question.
However it requires 500 reputation to get the Retag questions privilege and see a 'retag' option in the question. Simple editing the tags does not give you any reputation.