My hometown airport, Grand Forks Int'l (KGFK) has a rather large hill in the middle of it (in FS9) and if anybody knows anything about North Dakota, they'll know that ND doesn't have any hills.  I want to remove this hill and flatten it out, like it actually is.  I've been trying to comprehend some tutorials but it just isn't clicking with me.  What program should I use and what's the best way to do this?

Any help is greatly appreciated

perfect, thanks