Trying to delete my Apple account. They made me call a person on the phone to do this. On hold now.
...Wow. Madness.
They wanted to know why, and now I'm being escalated to a senior person.
They told me they are unable to delete my account nor any data from it because it was once used to sell an app (this was 10 years ago fyi), because they need to retain financials for a duration of time they couldn't tell me about.
I asked if they could delete the account after that duration passed. They said they aren't permitted to discuss that with me, and said I'd need to call their legal department.
I asked if they could ask the legal dept how long financial records would need to be kept before deleting my account. They would not tell me.
I asked if they could delete all account data EXCEPT the financial records. They said that they could not do this.
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I can't say I'm surprised. Past experience also confirms that big companies seem to REALLY not want you to delete your data anymore. Isn't that WILD though? 
@nleigh I don't know enough about GDPR to say. I wonder if there's a loophole for them if the account contains financial/tax info that they need to retain.