You can delete a single location or all locations.
To delete a single location - tap the Location's list button in the low right corner of the app's main screen.
Find the location you want to delete and swipe it left or tap on it and tap the minus button. Then tap on the Delete button to delete the location.
Alternatively, you can delete all added locations. For this you need to tap "Remove Pins from Map" button in the bottom left corner of the Locations list screen: