"All the programming thingies" are not at all difficult, at least in this case. You just need to copy the "CivilizationInfos.xml" from the default Assets/XML/Civilizations folder to your Custom Assets/XML/Civilizations folder. Don't edit the one in your default Assets folder, you'll mess up your game.
Then use Ctrl+F to find the civilization/leader you want to remove. If it's a civ you don't want to see, you can replace the 1's in "<bPlayable>1</bPlayable>" and "<bAIPlayable>1</bAIPlayable>" with 0's. If it's just a leader, do the same for the "<bLeaderAvailability>1</bLeaderAvailability>" line. (Better not leave any civilization still playable but with no leaders though...)
I did this for my game for the Native American Empire, but not because I hate playing as or against them. I just think it's a silly civilization. If they had gone with Sioux or Iroquois, I would leave them alone. Personal preference...