Two-step authentication is standard on iOS 15 or later.
Please follow the steps below on how to delete the authentication code when resetting.
1. Please tap "bitbank.cc" in "settings→password".
2. Please tap "編集" at the upper right corner.
3. Please tap the red circle icon that appears in the confirmation code field.
4. Please tap "削除" in the confirmation code field.
5. The confirmation code has been deleted and you can reset a new one.