Instructions
Go to the "Wii" button at the bottom left of the screen. Press the "A" button to access the section.
Find "Data Management" in the new menu and press "A" to access it.
Find the "Wii Channels" icon in this menu with the Wii remote. Press "A" to access it.
Find the Wii Channel you want to delete and select it. Click "Erase" to get rid of the channel.