Existing Account Issue

[Grumps]

I've recently reset my gameplay by simply deleting the app and deleted it from my Game Center. I manage to start a new city after but each time the app goes into background and come back up. I will get a popup saying.

Existing Accounts

We can't connect you to this GAMECENTER account because it has already been linked to an existing game.

Can NEXON help me remove this link so I can start backing up my game and play it across multiple devices again? I no longer intend to play my old city (due to wrong Nation choice)