Unable to delink AD/SAP account from Employee account

Hello,

I have to delink AD account/SAP account from employee account since the user has 2 AD/SAP account.
I tried to delink using the option "Assign Active Directory User Accounts" but I got an error saying "ADSAccount: Write permission denied for value UID_Person" while saving it. Is there any other way to delink AD/SAP account from employee account?

Thanks