Since Game Packs are installed directly from the Origin Client, uninstalling add-on content is only possible by uninstalling The Sims 4. Once you re-install the game, you can pick and choose add-ons to install again.
To uninstall The Sims 4, right click the game in the Origin Client and select “Uninstall”. This also removes any additional add-ons and game packs you may have purchased for your game. Uninstalling the game this way should not delete any of your game files, however, Crinrict suggests backing up your Sims 4 Folder.
NOTE: DO NOT use non-official methods which suggest deleting folders in the File System. It has not been tested, is known to generate warnings, and can cause issues with your game. Completely uninstalling The Sims 4 is the only official and safe way to uninstall content at this time.