Sims 3 DLC, do I have to use the expansion packs in the bundle?

There is a way to disable The Sims 3 Expansion Packs, but it's weirdly and unnecessarily complicated. Moreover, in all probability your saved games will not work afterwards.

This was originally written for Windows 7, but the same steps more or less apply in 8 and 10.

1. Shut down The Sims 3 completely.
2. In your Steam Library, right-click The Sims 3 and choose Properties.
3. In the ['DLC' tab], untick the EP you don't want to use any more then close the Properties window.
4. Create a System Restore Point (in Windows, right-click My Computer or your version thereof; select Properties; select System Protection; click "Create").

[As extra precaution, backup your registry and The Sims 3 saved games here! Disabling EP's is essentially the same as disabling mods (in other games), and your saved games could become useless.]

5. In Windows, use your "Find" charm or "Run" box to run the program regedit.exe.
6. In Registry Editor, go to File > Export and save the file to somewhere you can find it easily. This is in case something goes wrong.

7. In Registry Editor, navigate to your Sims 3 registry keys. This is normally found under: HKEY_LOCAL_MACHINE > SOFTWARE > Wow6432Node > Sims(Steam)
   

8. There you will see a list of all [Expansion Packs] and [Stuff Packs] that you have installed. Right-click the EP you want to uninstall, and choose "Delete".

9. After this, your game should start normally.
   • For details on restoring your registry, if it got messed up, see this page.

Alternatively - and this is pure guesswork - if you don't want to edit your Windows registry, and bandwidth and data limits are not keeping you back, you can uninstall the game after step 3, and Steam should redownload only the files of the EP's you have selected.
I guess you can even make a backup of the game folder, uninstall the game through Steam, move the backup to its original position, and let Steam reinstall. I don't think it will even be necessary to remove the folder of the EP you don't want, since it's not selected and should not load (but you can to save space, of course).

^{(NB I'm not sure these non-registry-altering solutions will work, and I can't test it. If they do, please leave a comment with your experience. It seems to have been done successfully here, however)}

As for the cheats, they still work.
Open the console by clicking Control+Shift+C
And type in any of the cheats. Like these:

kaching = Adds 1,000 simoleons

motherlode = Adds 50,000 simoleons

familyfunds x = familyfunds only goes up to 99,999,999.

For some you'll have to enter testingcheatsenabled true for them to work:

moveobjects on / off = Allows you to move or delete any object.

freerealestate = When building a house in World Edit , this cheats ignores the the price of the lot. Making the lot free.

More can be found on the linked page.