Be aware this just shows creating a basic new Sims 3 folder. It will not have your Saves, SavedSims, Mods, Downloads, Library or Store items installed. You will need to copy those folders over to the new Sims 3 folder and reinstall your Store items and custom content that is in .Sims3pack format.
– Read
this post if interested in downloading a new Sims 3 folder with mod folder already added.
Click images to see larger view.
Showing my Electronic Arts folder, before any changes:

1. Rename your current Sims 3 folder (right-click the folder and select Rename.) For example Sims3-Current.

2. Open Origin go to your Game Library, double-click on Sims 3 and exit the game at Sims 3 Main Menu, or double-click on the Sims 3 launcher icon to open it and close it after it loads. -- This creates a new Sims 3 folder.

3. To use this new folder copy the Options.ini file from your renamed (Current) folder to your new Sims 3 folder. So you have your graphics and game settings.
-- To do that, right-click on file, select Copy and paste it into your new Sims 3 folder.

** All your saves, mods/cc and Sims will be fine in your renamed Current folder. - The new Sims 3 folder is highlighted in Blue. To show that your Current folder is still there, it's highlighted in grey.

Both the Current folder and new Sims 3 folders are separate from each other. So anything you do in your new folder, won't affect files in your Current folder.
-- To copy over the folders and files, right-click on one at a time and select copy and paste into your new Sims 3 folder.
* For a list of files and folders to copy back, please see the post below.
It's recommended that if you're having issues with any store content, to reinstall them into your new Sims 3 folder so it can renew the cache files in the DCCache folder.