Hey @Ali-MK03 Welcome to the Forums!
Apologies for the delayed response and sorry to hear that you have linked your Ubisoft account with your secondary PS account.
Once you link your Ubisoft account with a PS account, the linking is permanent and cannot be unlinked any more. However, there may be an exception that can be made with unlinking the accounts. For that I would advise you (if you haven't already) to create a support case and provide all the details regarding your Ubisoft and PS accounts, so our colleagues can take a closer look into this.
Please bear in mind, that if you have played the game on the Ubisoft account, which is linked to your secondary account, all the progression is merged (as of 06.12.2022) and if you decided to link your account with another account, the progress and content will remain on the account, on which the accounts were previously linked after the cross progression was released.
Should you have any queries, please let us know!