Click Start, click Run, enter regedit. Navigate to the key HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main.
In the right-hand pane find a value named Window Title.
Double-click it to change its data.
Either delete the text entirely or change it to something that pleases you.
If you don't see the value, right-click in the right-hand pane and choose New String Value. Name the value Window Title and then proceed as above.