The URLs that appear when you start typing in Internet Explorer's Address Bar are drawn from two locations, your browser History and a Registry key that records URLs you've typed directly into the Address Bar. First, click on the 'History' button on the toolbar to open the history bar at left. Click on the 'View' menu and select 'By Site'. If the unwanted URL is present, right-click on it and choose 'Delete'. If the URL wasn't in History, or if deleting it there does not prevent it from showing up in the Address Bar, you'll need to remove its reference in the Registry. Launch Regedit from the Start menu's Run dialog and look for this key:
The values in the right-hand pane have names like url1, url2, url3, and so on. Scan the list to locate the one that contains the unwanted URL, take careful note of its name, and delete it. Now you need to "patch" the list to eliminate the gap created by deleting that name. Find the value whose name includes the greatest number. Note that the values are sorted as if they were text, so url10 comes before url2. Change the name of that highest-numbered value to the name of the value you deleted. If you don't do this, IE will ignore the items after the deleted one.