Step 1: Go to the Shut Down menu and click 'System Settings'.
Step 2: Inside 'System Setting', find 'Appearance' option and click it.
Step 3: Go to 'Behavior' tab.
Step 4: Turn the 'Off' button to 'On'.
Step 5: Now, unity launcher should hide. Whenever you move the cursor to the left side of the screen, unity launcher will appear again. One can adjust it's sensitivity by moving along the side bar.