Deleting an exchange account from mail on iphone

I am trying to hibernate a mail exchange account on my iPhone XS running OS12.1.2

Ive left the company but want to keep the mail and contacts etc on my phone.

the request for the password keeps coming up twice on my phone every 5 min...

The issue. When I go to the options to turn off the mail, it won’t allow it to be turned off. The slider moves then slips back to on.

The contacts, reminders, notes etc as if I want to delete off the iPhone, I agree, then it comes back to on again...

why is is this happening?

how can I turn the mail off without fldeleting off the iPhone?

thanks Dan 🇦🇺