1. stop using icloud for synching and storing stuff (since it goes through Apple and is not E2E encrypted as your devices don't share keys)

2. stop using publication stuff (gamecenter) since that's literally public information Apple broadcasts for you

3. that's about it, the rest is various accounts information e.g. your appstore/itunes purchases, your retail stuff, repairs, … basically your files at Apple, the only way to request that Apple does not generate it is to delete your account (which the portal lets you, there's an option to nuke your account entirely and permanently) and stop interacting with Apple entirely, or at least in such a way that they can link things together (e.g. appleid when purchasing devices, that kind of stuff)