How to erase saved games for Sims3

You can also delete them from within the game.

To be exact, the saves can be found here: documents\electronicarts\thesims3\saves

Each savegame has a folder in there. You could also move the folders you don't play anymore to an external drive so you can recover them later.

To save disc space, it's also a good idea to clean out your DCBackup folder. The only file you need in there is the ccmerged,package. Make sure to keep that, delete the rest. They serve no purpose.

You can also move the files in the downloads folder to an external drive since once you installed them, the only purpose of those is to have them safe somewhere. You can put them back, should you need to reinstall your stuff.

Here's a thread that explains the user files in more details: http://sims3.crinrict.com/en/2011/01/faq-user-files.html