It was actually due to this that I tried to close my Robinhood account (that was never used), and realized... it's actually not possible. I tried to invoke CCPA, and over a 19 email thread, got frustrating and contradictory replies, such as when I asked how to end my relationship with Robinhood (per their privacy policy, they keep data up to 5 years after the relationship ends):

"When your account is deactivated, you and others can no longer use it to trade or transfer, but the account still exists, and we still treat your relationship as ongoing."

"closing your account ends your active brokerage relationship"

And then when I asked them to clarify which of these is accurate, they sent me a generic non-answer.