Cannot remove email autofill - Iphone\Pad

IOS 9.x.x

This applies to Google (Gmail) & Exchange based mail accounts.

When you start addressing a new email message (typing in the first or second letters of the email address) using either of these account types on either an iPhone or iPad, a listing of email addresses displays as a hint list -- any of which could then be chosen to address the email message. As I understand, Apple calls this feature "Autofill".

The problem is, how does one go about removing an email address from the Autofill list?

I have spent far more time than should be spent on such a simple and basic function. I've come to the point where I don't believe there is a way to do this.

I have seen references to Mac based email, Safari and so on, but none of these apply to the Google or Exchange Mail services.

I have been able to confirm through testing that this list is stored on the iDevice itself and is independent of the Google or Exchange services -- IE the Contact lists of those services. This was done by removing all Email account information from an iPad and then removing back in a Google account. The newly added Google account picked up the same Autofill entries as before the accounts were deleted. I removed the Google account and added in an Exchange account and the same Autofill entries were displayed. So, clearly the Autofill data resides on the iDevice -- after removal of all email based accounts.

So, question is, is there a way to remove old Autofill entries that are no longer valid?

Thanks.