If you're like most people you have Outlook open literally all day (and night). There is no need to have Outlook take up space in your task bar when you aren't using it “ have it minimize to your system tray.

Click on the Outlook icon in the system tray (look in the bottom right part of your screen) with the right mouse button.

Select Hide When Minimized from the menu.

Now, when you minimize Outlook is will disappear from the task bar. To open Outlook again, double-click on the Outlook icon in the system tray.