1. From the Main Menu, select the
Wii icon on the bottom left of the screen.
2. Select
Wii Settings.
3. Click the right arrow 2 times to get the the 3rd page of the wii Settings.
4. Select
Format Wii System Memory.
5. Confirm by selecting
Format.
Be aware that this will not delete your Wii Shop Channel information. To do that, you must follow these steps.
1. Select the
Wii Shop Channel from the Main Menu.
2. Select
Start.
3. From the
Wii Shop Channel menu, select
Settings.
4. Select
Remove Wii Shop Channel Account.
5. Select
Remove to confirm the removal.
The manual recommends removing the Wii Shop Channel information first then formatting system memory if you are transferring or selling your Wii console. Hope this helps