There are two types of data that can be stored with the built-in memory of your Wii console: Wii Channel Data and Save Data. In the event that available blocks left on your Wii console are not enough to add new games or channels, you can free up some space by managing these two types of data. Keep in mind that some games and channels are stored as both Wii Channels and Save Data. If you want to completely remove either of these, you will need to delete it from both areas.
Wii Channels
The Wii's main screen displays all of the available channels on your Wii. These are a combination of channels that come pre-installed on the Wii, additional channels downloaded through the Wii Shop Channel (such as the Internet Channel and Nintendo Channel), Virtual Console and WiiWare titles, and channels downloaded from specific Wii games (such as the Mario Kart Wii Channel). Any channels that you have added to your Wii can be managed through the "Channels" option of the "Data Management" section of the Wii Settings. The Mii Channel, Photo Channel, News Channel, and Forecast Channel that come pre-installed on the Wii cannot be changed.
If you would like to free up some additional space on your Wii console, you can delete any Wii Channels you are not currently using. This does not mean they are gone forever. There are two ways to get them back. With both ways, as long as you still have the Wii Channel's save data, you'll still have your game progress (including in-game "suspend" saves) or saved channel settings available should you add the channel back to your system.
Download it again
Any Wii Channel you downloaded from the Wii Shop Channel, which includes Virtual Console or WiiWare games, or channels downloaded from a Wii game disc, can be deleted to free up memory space. Should you wish to get the Wii Channel back, you can simply re-download it later.
Copy the Channel(s) to an SD Card
Most Wii Channels, including Virtual Console or WiiWare games, you downloaded from the Wii Shop can be copied to a compatible SD Card. This gives you the ability to delete that channel, and then copy it back over from the SD Card to your Wii should you wish to use it again at a later time. Please keep in mind that any Virtual Console or WiiWare title you copy can only be played on the Wii console it was originally downloaded to from the Wii Shop Channel. (Be sure to copy the Wii Channel back over to the Wii when you wish to use it again; simply having the SD Card inserted with the channel on it will not allow it to be used.)
Save Data
Located in the "Save Data" section of the "Data Management" area of the Wii Settings, Save Data are the files created when you save a game's progress (such as high scores, items found, and where the game last saved), as well as data for certain Wii Channels (such as your voting results in the Everybody Votes Channel, or your "Favorite" sites you've book-marked on the InternetChannel, etc.). This data is stored in this section separately from the Wii Channel data, and can be kept, copied, or deleted independently of the Wii Channel it is used for.
If you would like to free up some additional space on your Wii console, you can delete any Save Data you are not currently using. There are two ways you can free up space by managing Save Data:
Copy the Save Data to an SD Card, then delete it from the Wii
Most Save Data, including Virtual Console or WiiWare save files, can be copied to a compatible SD Card. This gives you the ability to delete that data, then copy it back over from the SD Card to your Wii should you wish to get it back at a later time. (Be sure to copy the data back over to the Wii when you wish to use it again; simply having the SD Card inserted with the data on it will not allow it to be used.)
Delete the Save Data permanently
If you are not interested or unable to backup the Save Data for later use, you can permanently delete the Save Data. Please be aware that by deleting files in the "Save Data" section without first copying them to an SD Card, there will be no way to get them back. If you decide to play the game or use the Wii Channel again, all your previous data will be lost.
Additional Information:
How can I tell how many memory blocks I have available?
You can view the total amount of free memory blocks by going into the the "Data Management" area of the Wii Settings. Once inside "Data Management", select "Channels" to see the available space in that section listed as "Blocks Open."
What about Nintendo GameCube save data?
Nintendo GameCube save data are stored on Nintendo GameCube Memory Cards, and do not affect the amount of free memory blocks on the Wii console. For help working with Nintendo GameCube Memory Cards, click here.