You're talking about Dell Dock:
It is a free of charge tool developed by Dell that allows you to organize and personalize your desktop. In order to download it, navigate to the official web page, click the blue Download button, save the file to your computer and isntall it following the on-screen instructions.
Note: If you're disabling by mistake the toolbar, navigate to Start, type services.msc and open the utility. Locate the Dock Login item, double-click on its icon and enable it.