The user interface in Internet Explorer 7 does not allow removing the Command Bar. In case you ever wanted to remove the Command Bar, here is the registry hack to do so. Be sure to read the caveats mentioned in the article.
HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\CommandBar
This method removes the entire Command Bar, which includes the tabs and the two Favorite icons. Use this only if you're not using the Tabbed browsing feature.
HKEY_CURRENT_USER\Software\Policies\Microsoft\Internet Explorer\Toolbars\Restrictions
Important Note: The above branch does not exist by default. You need to create them manually, or use the REG file at the bottom of this page to automate the setting.
You can automate the above using the REG files available at the bottom of this page.