Problem: After login in the Ubuntu Linux system, the Unity launcher stays at the left edge of the display. It does not auto-hide.
Solution: Click on the Settings icon in the top right corner of the display. You will find tabs like Wi-Fi, Bluetooth, Background, etc. in the left column. Click on Dock. In the right column, there will be a swich, saying, "Auto-hide the Dock". Set the switch in the ON position. This should solve the problem.
In earlier Ubuntu versions
Click on the Settings icon in the top right corner of the display. Select System Settings. In the next window, Personal, Hardware and System application icons are shown. In the Personal Applications area, launch the Appearance application. The Appearance application has two tabs, Look and Behavior. Select the Behavior tab.
The Behavior tab gives the
Auto-Hide the Launcher option. There is a horizontal slider button to set auto-hide of launcher bar off and on. Set the button to the ON position. Set the Reveal Location as Left and set the Reveal Sensitivity as low.