Wrong Square Enix id on ps4

Hi. I am currently playing FF 14 on my pc. I decided to buy the game for ps4 so i can play my same account on the ps4 on my TV. I partecipated at beta phase 1 and i had to create a new account in order to play in the beta.

Now, I deleted the old beta client and bought on psn the game and installed it.

When i launch the game, It tell me that I have an existing account, It show me the login page with the old login square enix ID. I don t wanna use it cause It was only for test the beta, and I can't change it from ps4 cause there is no possibility to change it.

So, I saw you can link the square enix account to psn, I went to the page but It tell me
Account linking failed. This may be due to your PlayStation Network account being incomplete.
I already linked steam account with no problem at all.

How I can change the square enix ID on ps4 so I can play with my pc avvount?