Detail of expectation of 'Delete Account Feature'

As per policy mention in Apple Store guideline in section 5.1.1 related to Data Collection and Storage, it is mentioned to have Delete functionality within app if account creation option is present.

I am facing challenge for one of my enterprise app developed for the client, where account creation and sign in feature is present, but that login credentials are 'inter-link' to multiple other client's websites/tools/applications.

In this case if user delete the app, it will unconditionally delete from all others too, without knowing that to user.

Is there any way that we can get clarity on below points:

1. If we implement with delete option only setting up a flag in app that user won't access with same ID login? Like a 'soft delete'?
2. If user not creating account from app but still able to login with existing account with client ID, still delete feature would required?
3. What are more expectation and details which Apple will going to check for Account Delete feature?

Thanks in advance.