To delete a map that you already have downloaded, you can do that one of two ways.

1. Open the map by clicking on the spyglass icon at the bottom of the screen.
2. Click on the folded map icon in the lower right of the map
3. This opens the map options, and choose "Offline Maps"
4. Now you will see any maps you have downloaded (and the option with the + sign to add more).
5. Open the one you want to delete, and there is the option to VIEW or DELETE.

The second way is to access the offline maps inside the PRO TOOLS tab in your profile. You can add and delete from here, too, as in the steps above.