Instructions
Download AnyTitle Deleter from the WiiBrew site.
Extract the contents of the archive to the "Apps" directory on your SD card. If you do not have an apps directory, right-click and click "Create New Folder."
Insert your SD card in your Wii and launch the HomeBrew Channel. Select "WAD Manager" and choose "AnyTitle Deleter" to launch the program.
Use the arrow on your Wiimote to scroll down to the title you want to delete, then press "A" to delete it.