How do I get rid of auxiliary tool bar?

If you have enough real estate, in portrait screen mode, you can drag and drop it below the color swatch in the left tool bar, and it will dock into the existing bar. However, if you then rotate the screen to landscape orientation, the bar will come undocked, since there isn't enough room for it then.

This extra bar only appears with certain tools, and can be moved anywhere  on the screen. It has all the options for the active tool, so there's no way to hide it.