How can I delete wii channels?

Ok, I started to download a demo game from the wii channel, but for some reason it was inturrepted and it told me that I could try again without using any blocks. So I tried again and it said I would need to download using some blocks but then it also is in my list of already downloaded channels. So I just want to delete to get my blocks back. I also would like to delete some channels I already have on my wii home page, the everybody votes channel but how do I do it. Sorry if this is confusing but try to answer as much as you can thanks.