One way to activate the auto- hide taskbar option is via the registry. However, it should be noted that this method is technical in nature and does require some code and registry knowledge.
Go to Start and then select Run. In the Run input type regedit
when you enter into registry there you would see the files and folders viewable, then in the registry you may search for HKCU\Software \Microsoft\Windows \CurrentVersion \Explorer\ StuckRects2
once you put the registry key, you will be directed to the Settings. This value is a REG_Binary type. Within this you need to find the settings for the taskbar, as well as you could also make the settings for icon size and icon placement.
whatever the value you put it will get written only when your computer log offs, and it would be difficult to catch the value. You will first have to fiddle around with the environment and then export the data.
Once you have located and exported the data, test to see if the taskbar works properly.