You can't just "turn it off", you'll have to remove it from the template files. The easiest way to shrink it (ie. to remove the logo and make it more pretty, like the one you see at this site) is to use my
Compact Headers hack, then you can add your own stuff in using the Header and Footer fields of your Style Templates control panel.
1QuickSI, this question belongs in this forum just as much as it does in that other forum.
---Jamin