Hi @philipthecooper - I think you have SimCity with Cities of Tomorrow expansion? There's no way to completely remove the CoT expansion.
The best way to avoid the CoT expansion items in-game is to just not use them. Don't use anything with the blue pattern behind the icon, which designates it as a CoT item. When you place one of the items, it will begin to futurize the area around it, and new construction will be built with the futuristic theme.
Be aware, if you play multiplayer online, other regional players may use OmegaCo factories which will eventually send drones to your city, too. So if you don't want any of the futuristic items, I would recommend either opening a private region online so you can ask the other players not to use CoT items, or play in Single Player/Offline mode.
Happy Building!
**edit - I moved your post to the SimCity 2013 forum, since the forum in which you posted is for other versions like SimCity 4.
