@graceg30 The only supported way to uninstall a pack is to uninstall everything and then reinstall everything except for that pack. Origin may still try to redownload the missing pack though, particularly after a patch or after you clear Origin's cache. You can cancel the download, if you see it in time; the issue is it sometimes restarts when you load the game to the Main Menu, so you'd need to alt-tab back to Origin to cancel.
You can also just delete the folder for a given pack. While this isn't supported, it does usually work. The worst that should happen is you need to repair the game and redownload the pack. The Vampires folder is labeled GP04 (Vampires is the fourth game pack), and unless you changed the default install location in Origin, the full file path will be:
Program Files (x86)\Origin Games\The Sims 4
The other option is to disable the pack from loading. This can be done through Origin, and undoing it just means deleting the command line argument.
https://sims4.crinrict.com/eng/2017/03/disable-single-packs/
