Yes. We will delete everything.
It feels very dishonest to say that you delete the user's data, while handing it over to a third-party ...
For what it's worth, I actually like Plaid's API compared to Yodlee, but have serious concerns about privacy. There's no way to determine if they are _just_ collecting transactions when you request the user's transactions as a dev. The user is handing over their user/pass/MFA and Plaid could be doing god knows what with that.
Beyond audit by a third party, how would one go about proving they deleted something and absolutely no other copy remains?