Sign into your old account on the internet
?Click on "Your Account & Help" (top right corner of the webpage)?Under "WATCHING INSTANTLY ON YOUR TV OR COMPUTER"?click on "Manage Netflix ready devices and computers"
?Deactivate your WII
On your WII go to the Netflix channel and follow the steps and it will give you an activation code for your new Netflix account.
Read more: http://wiki.answers.com/Q/How_do_you_change_netflix_accounts_on_wii#ixzz1SlO cG7w8