Start Killer removes the Start button from your taskbar. When you run Start Killer it removes the Start button from taskbar to give you additional space on taskbar. When you close Start Killer the Start button is visible again.
Though the Start Button is removed, you can still open the Start Menu using CTRL+ESC or WIN key. Start Killer places an icon into the system tray. Right-click on the icon to close StartKiller or to open the Settings dialog. You can remove the icon from system tray. In this case use CTRL+ALT+SHIFT+F12 to open the settings dialog box.
Start Killer is free, you can use this utility as you want.