Get something sharp (like a knife, or a scissor), and cut it in pieces.
This has been asked over and over again, do some research, PLEASE! There are various Tools to convert a Wii-Image, Wiimms ISO Tools can convert your ISOs to all of them. Which format you want depends on what you need. If you want to be able to play them with an USBLoader, you should go with WBFS or a sparse ISO, both supported by most loaders, and both remove the Junk-Data, which won't result in a proper 1:1-Image (still, the games will play fine). You can also remove the Update-Partition to make them even more smaller. If you want to be able to play them with UNEEK/SNEEK, you can go with the RAW/FST-Format (basicly unpacks the ISO). If you just want to make your Games smaller, and store them on your HD (but not play them) and want to keep the Junk-Data, Wiimms own Format, WIA, is a good choice. So, check Wiimms Tool out, and make your choice.