By default in Ubuntu, the Unity launcher is placed on the left side of a screen. We can’t change the position of Unity in Ubuntu 15.10 and older versions. But from Ubuntu 16.04 (Xenial Xerus), we can move the location of Unity launcher from the left-hand side to the bottom of the screen. However, there is no built-in option in System Settings to move the Unity launcher. But by using the following terminal command we can move the Unity desktop launcher.
To open the terminal window, press CTRL, ALT, and T on your keyboard. Then run the following command in your terminal to move the Unity launcher from the left-hand side to the bottom of the screen.
gsettings set com.canonical.Unity.Launcher launcher-position Bottom
You can also revert back the Unity launcher from the bottom of the screen to the left-hand side. Here the terminal command to do that,
gsettings set com.canonical.Unity.Launcher launcher-position Left
Note: Currently, it is not possible to move the position of Unity launcher to the top or right-hand side of the desktop. Hope this feature will add in the future.
Hope this helps.