You can link your My Nintendo membership or remove your Wii Shop Channel Account.
Linking Your My Nintendo Account:
My Nintendo members can link their membership to their Wii Shop Channel
Account to automatically register Wii Shop Channel downloads to their
My Nintendo account. By linking your My Nintendo User Name, you will be
able to participate in a variety of activities, promotions and
programs. Please review the Wii privacy policy for more information on
linking accounts.
*If
you've forgotten your My Nintendo User Name or password, please visit
http://my.nintendo.com and use the "FORGOT YOUR PASSWORD?" feature.
Unlinking Your My Nintendo Account:
You can unlink your My Nintendo membership from your Wii Shop Channel
Account at any time. By doing so, your My Nintendo membership will
remain intact at Nintendo.com. If you do unlink your My Nintendo
membership, you can always re-link it to your Wii Shop Channel Account
later.
Removing Your Wii Shop Channel Account:

If
you remove your Wii Shop Channel Account, all of your registered Wii
Points and downloaded software will be deleted, and you will not be
able to re-download the software for free.

If your Wii console is transferred to another person, your registered
Wii Points and software that you have downloaded cannot be transferred,
so your Wii Shop Channel Account will first have to be removed.
Caution: Once your Wii Shop Channel Account has been removed, you will not be able to recover it.