To save the coordinates of a specific location on the world map, follow these steps:
1- Click on the desired location.
2- Click the star beside the coordinates.
3- Choose under which category to save the coordinates, and pick the name you like.

To access your saved coordinates, click on the file icon at the bottom of the world map screen. Slide it from right to left and click the delete icon to delete specific coordinates.

Note: If you delete the game, you will lose your saved coordinates, so as a precaution, you can take a screenshot of the list before doing this step.