To undock your keyboard, follow the steps below:
- Open Toolbar by tapping the '+'
- Tap the 'Settings' cog
- Tap 'Float'
Move the keyboard around the screen by dragging the circle button. Your keyboard will dock/undock when this circle is tapped.
Note: From SwiftKey 7.1.4 onwards you can no longer undock your keyboard while using 'Thumb' layout.