Good luck with this. I have the opposite issue. I was in USA region for FFXI, but now am in Australia which comes under EU. I spoke to EU live chat last night who told me that they will not do Region changes, so the only options are to
1. - buy a new NA collectors edition of the game so I can continue playing my early access characters (that was a whole other issue...my pre-order code didn't work, but SE counted it as redeemed anyway, so a US friend had to get me a US pre-order code). Oh and the NA Square Enix site will not let me buy a NA copy anyway as my IP address is wrong for that region.....
or
2. - make a brand new account and apply my physical EU collectors edition code to this account. This would mean losing my characters, my pre-order bonus items, but most of all I would no longer be able to play with my son and partner as that server is closed to new characters.

That something so simple as a region change is not possible is beyond my comprehension. I still don't get why this artificial regional locking exists anyway.