With iGoogle, you can set a theme to your home page on Google. When you first select a theme, they give you a link to undo the selection and go back to whatever you had before. But nowhere will you find a command that allows you to completely remove the theme you have and go back to the "classic" Google home page. If you want to go back to that, you have to click on the "Select theme" link. When you do that, the "Classic" theme will always be shown as the first option. Select this and you'll be back to as if you have never selected a theme.