On my iPad's original email app somehow a friend of mine email address recorded as a wrong address.

So, I am trying to delete that wrong address by following the instructions and opened the CONTACTS app and address is NOT there. But when I want to type an email to that person as soon as I put the first letter of their name autrofill places the oval shaped mail label immediately with that wrong address.
But of course all I see the nickname of the account.
So please help me if it's possible to find out where those email addresses stored in my ipad address book and delete them.
Thanks in advance...

when the auto fill pops up, if its wrong you can just click on the suggested word to cancel the auto correction.

I believe this is a bug. Otherwise users are going to have all kinds of incorrect or unwanted addresses. I have the same problem.

This is a well-known 'feature'/'issue'/'bug'. The iPad Mail app 'tries' to be helpful by remembering recently used email addresses and prompting you with them. The Mac version does the same but it has the capability for the user to delete these 'recently used' email addresses. That capability was not included in the iPad version of Mail.

These recently used email addresses are not put into your list of contacts, so there's no known way of accessing them. However there is a little bit of good news. This list of recently used email addresses does eventually expire. No one seems certain whether the expiry is by date - i.e. the entry was made more than so many days ago - or by number of entries - i.e. the list is only of a limited length - but expire it does. Until then you have to grin and bear it.

Tim