iOS players can uninstall the game by signing out from Game Center and then install and launch the game. This would cause a new local save file to be created. At this point, they could close the app and log back in to Game Center and it will ask if the player wants to overwrite the save that linked to Game Center. Please select Overwrite. This will allow a new account to be linked properly and the old one overwritten.
On Google Play, players will need to remove the Google Account they used originally from the device, uninstall and reinstall the game, and then launch it to create a new local save. The player can then re-add their Google Account to the device and close and re-launch the app, and then choose to overwrite the account when presented with the account conflict screen.
And finally, if socially linked, please reach out to customer support and the team can manually uninstall and then reinstall the game to create a new local save that will link socially when the players launches the game again.