The easier way to do that would be to have a separate save file that you play with basegame only.
When you want to play that save, set Origin or EA App or whatever to load the game with no packs.
When you open the game and see the Load Game screen, there will be some sort of indicator on the saves that used your packs (maybe it's a light green icon, I can't remember). Nothing about those saves will change if you don't load them.
Then when you do want to play those saves, you can set Origin or whatever to load the game with all your packs.
