World Clock Deluxe lets you add its icon to the menu bar so that you can quickly access your clocks.
Choose World Clock Deluxe > Preferences, and then click Menu Bar.
Select the "Show clocks in the menu bar" checkbox.
To display clocks, click the World Clock Deluxe icon in the menu bar: all your clocks will appear in the menu. If you want, you can customize the menu so that it lists only the clocks that are visible in the menu bar.
On macOS 10.12 or later, Command-click the World Clock Deluxe icon in the menu bar and drag it.
On macOS 10.11, use the Position pop-up menu in the Menu Bar pane of World Clock Deluxe Preferences. Choose Left to force the World Clock Deluxe icon to always appear to the left of all your other status items. Choose Center to position the World Clock Deluxe icon between your status items and Apple's menu extras. Choose Right to display the World Clock Deluxe icon to the right of all menu extras.
Customize the World Clock Deluxe menu in the menu bar
Show and hide clocks