How can I get rid of Sims4 add ons?

mazikeenee​  The Sims 4 Packs folder only exists in macOS.  For Windows, each pack has its own folder inside [install location]\The Sims 4.  You can see the install location in the EA App, under Sims 4 > Manage > View properties.

I've also seen an Uninstall button recently under Manage > Manage add-ons, so you can try that again now to see whether it's shown up for you as well.

If there isn't a button there, you can delete the packs' folders in the main Sims 4 folder, but the EA App may try to reinstall them, so watch for that and cancel the downloads.  If that doesn't work either, there's an unsupported and kind of janky workaround that I can write out.