how to fully delete user account?

[William Mattison]

The language for a user account was set to simplified Chinese.  Not what was wanted!  So I thought I could just delete the account and re-create it.  I used the Users and Groups GUI to delete the user account.  I did check that the home directory for that account was gone.  Then I re-created the account with Users and Groups.  When the user first tried to log in, everything was in simplified Chinese!  I re-tried all this with an added reboot between deleting and re-creating the account.  It was still simplified Chinese.  All other user accounts are English.  Where is the language preference for that one user account "remembered" even after the account is deleted, and how do I clear it?  No one here knows enough simplified Chinese to read/understand the simplified Chinese menu entries, buttons, prompts, messages, application icon labels, etc.  Or how can I as root reset that account's preferences back to default without becoming that user?

Thank-you in advance for your help.
Bill.