I'm wondering if you are referring to the Auto Complete Address Bar in Opera. Deleting the "typed_history.xml" file you mention doesn't unfortunately clear the items in the drop down menu.
If this is indeed to what you refer, then I find the best solution is to disable it completely.
In the address bar type "opera:config" (without quotes). Press enter. Scroll down to and select "User Prefs".
Scroll down again to "Auto Dropdown", and uncheck the box. Scroll to the end of "User Prefs" and select "Save".