Presuming you mean the Windows taskbar.....
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...right click the Start button (orb) select properties, select the taskbar tab from the task bar and start menu properties dialogue box, then check auto hide the taskbar. From this properties box you can also choose the location of the taskbar....bottom, top, left or right side of the screen.
You can also resize the taskbar by moving your cursor to the top of the taskbar and when it changes to a double headed arrow, drag up or down to resize.