Instructions
Deleting channels
Boot up your Wii and select the "Wii" icon in the bottom left corner of the menu screen by pressing the "A" button.
Select the "Data Management" icon using the "A" button.
Click on the "Wii Channels" option.
Choose the channels you want to delete, then press the "Erase" option to remove them from your Wii.
Deleting saved data
Access the Data Management screen by selecting the "Wii" icon, then the "Data Management" icon, as before.
Choose the "Save Data" button to bring up your save files.
Highlight the save data file you want to remove from the Wii, then press the "Erase" button.