Code:
{*<div id="left-bar">
{include file="customer/left_bar.tpl"}
</div>*}
comment out as above in content.tpl. Use webmaster mode to find the correct one. You will need to adjust the css accordingly. If you use Safari with developer tools its very easy to see what you need to change. One bit at a time, mind you, as you will end up in a right old mess.