Hmmm this article does only delete a part of a user's record, the AuthAuthority value, in fact. This article is useful if you have a user created in 10.2.x and migrated in 10.5.

Beginning with 10.3, Apple changed the way passwords are stored for more security. Before 10.3, passwords were stored in the NetInfo database, in the users entries, using the unsecure crypt hash. Starting with 10.3, passwords are using stronger hashes (SHA-1 and beginning with 10.4 a Salted-SHA1) and they are no longer stored in the users entries but in /private/var/db/shadow/hash, in a file which is named with each user's GeneratedUID (not the old unix UID, be careful). This folder is only accessible to root and the AuthAuthority attribute tells the system which kind of password you have.

So, if your user was created before 10.3 and you have migrated it, you may want to do what this KB article explains.