DC Demote failed Access denied

We're trying to demote two domain controllers 2008R2 in a domain ( domx.company.local )  that is part of a forest Company.local

We added two new domain controllers into domx.domain.local and tried to demote the two old one.

Both of them failed to demote with the error

Error - The attempt at remote directory server SRVDC02.domx.domain.local to remove directory server CN=SRVDC01,CN=Servers,CN=SITE,CN=Sites,CN=Configuration,DC=Domain,DC=local was unsuccessful. (5)

We checked that all the DC objects and the Site's folder have no flag to protect them from removal.

We are logged into the DC to be demoted as an Enterprise admin.

Any help on solve the issue is appreciated