Watch the video or check the text version below:
Tap the menu button → "Download maps". You will see the list of downloaded maps. You can delete the map of the whole country at once or choose a specific region. To delete a map:
Android
Tap and hold the map and choose "Delete" in the pop-up window.
iOS
Tap and hold the map and choose "Delete Map" in the pop-up window or use the swipe gesture.