This tutorial explains how to prevent Firefox from displaying a list of suggested websites when you type in the address bar. You can apply this setting for specific websites, or all websites in general.
Open Firefox, and click on Menu > History > View History sidebar. Type the name of a website in the Search field and press Enter. Right-click on the name of the selected website and then select Forget About This Site:
Click on Menu > Options, and go to Privacy. Clear the checkboxes labelled History, Bookmarks, and Open tabs shown below When using the location bar, suggest:
Once these options are unchecked, the auto-search options will be disabled.