There is a program named DFX Terrain EXP.
But it comes with several files that a lot of people do not even use.
So I decided to only remove the land that is used.
I removed from it only the 7 terrains that are used in Mod Delta Force Xtreme SO.
Just extract all this content somewhere to open the copy all folder and paste it inside your main folder (Delta Force Xtreme OS).