Citi Trusted Identity Already In Use

I am trying to enable Touch ID for Citi Mobile app for a credit card that I have. The problem that I’m having is after I sign in to the mobile app with my u/p and go to the page to enable Touch ID, Citi returns back this message:

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Citi Trusted Identity Already In Use

This feature is tied to another user ID on this device. You’ll need to unenroll that user ID before continuing.

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I used to have a checking account with Citi and used enabled Touch ID (on my iPhone) for that user ID. But now that I’ve closed my checking account with Citi, how do I unenroll that user ID from Touch ID?