Change how much information is shown in the clock
By default, Ubuntu only shows the time in the clock. You can set the clock to show additional information if you choose.
Click on the clock and select Time & Date Settings. Switch to the Clock tab. Select the time and date options you want to display.
You can also turn the clock off entirely by unchecking Show a clock in the menu bar.
If you later change your mind, you can get the clock back by clicking the icon in the very right of the menu bar and selecting System Settings. In the System section, click Time & Date.
Change the date format
You can also change the clock's date format to match the preferred standard for your location.
Click the icon at the very right of the menu bar and select System Settings.
In the Personal section, click Language Support.
Switch to the Regional Formats tab.
Select your preferred location in the dropdown list.
You will need to log out and log back in for this change to take effect.