Trading in old iPhone 10 max to AT&T

Hi I’m trading in my daughters old iPhone 10 max and having trouble erasing the content. It’s asking for her screen time passcode which she doesn’t remember so we tried to erase that passcode through iCloud however when she originally setup this passcode she had a different Apple ID password and she can’t remember that now. I was told the only way to clear out the phone is through Apple support. I appreciate any help.

Thank you, David

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