As of October 2018 (version 1.29) the button in @mvvijesh's answer no longer exists.

You now have 2 options. Right click the panel's toolbar (nowhere else on the panel will work) and choose "move panel right/bottom":



Or choose "View: Toggle Panel Position" from the command palette.

Source: VSCode update notes: https://code.visualstudio.com/updates/v1_29#_panel-position-button-to-context-menu