Ok so I had a base game with three expansions and a catalog. Later I wanted to uninstall expansions and install different instead. Tried uninstalling through control panel, but it didn't work - it said that I don't have enough rights. Tried with Admin profile, tried a lot of stuff. If I try to delete folders with expansions and then start the game, it's initializing error. Even when the game is deleted and then installed again, folders are still there, and stuff from expansions is in the game - half invisible, half laggy as hell (and deleting folders lead to initializing error again). No matter what I do, I just can't get rid of them.
Help me, please.

I would suggest the Wiki pages-game help- the sims3 -uninstalling. I couldn't explain it better.Good luck!

@psy_doge

Why did you want to uninstall expansion packs? If you play save game using expansion packs content, there will be possible corrupt or glitch.
Better clean uninstall all base game + Expansion packs then reinstall base game + Expansion packs you want, to avoid unexpected game behavior.

If you can't force uninstall EP via Control Panel, (I suspect this must be "Do not have sufficient access to uninstall") then you have to edit regedit.

I've never tried uninstall expansion packs, so you'd better follow the instruction precisely.

How to Uninstall All TS3 Games The links are dead, but you can take see the Registry code of each Expansion Pack tips from commenter below
Manually Uninstalling TS3 by EA

Why do that at all? Why not just use an anygamestarter? Like ralphaelninja's: http://www.modthesims.info/download.php?t=499140

Oh thank you for that thing!