1. Follow the instructions in the linked thread to decompress the Civ.exe.
2.The same thread there's list of Hex values for Civilization technologies/advances.For example the first dummy tech has value of 0x43.
3.In the linked thread it says the building table starts in the address 0x2D4CA (decompressed civ.exe version.475.01 , but all civDOS versions have the same table but the starting address may be different.) The name of buildings, spaceship parts and wonders are in text form. (Well I guess it depends on your Hex editor settings.) Scroll the list down till you see the Spaceship parts.
4. Again the linked thread states that tech requirement for the building is in relative offset 0x1C. That means 28th byte counted from the first letter of the name of the spaceship part. Replace that byte with hex value 43 for example. Do this for all space ship parts.
Now you should be able to play without spaceships. I haven't tested this though, but I'm interested to hear if it works. And how does AI reacts when it can't build the spaceship parts.