As stated in the guidelines, you also must delete the records on whatever backend system that stores data for that account. As stated in the same guidelines, you still need to comply to any local laws regarding data retention.
GeertB
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Afaik, TestFlight builds only can get expired, not deleted. It boils down to the same thing, except your next upload will need to be 543 or higher. If you use XCode for the upload to TestFlight, it's able to fix your versions numbers automatically for you.