To delete some that you have, just open up exports and remove the names of the maps that you no longer want- Unless they are maps that you have made- if thats the case, open up feralheart>media>terrains and delete or remove the folder with the names of the maps you wish to remove, then scroll down and find the names of the maps terrain and delete or remove it as well. the voila! Hope this isnt too confusing, XD