This was a Working Setup and you deleted the Administrator account ? or this was a new installed environment?
The Administrators account can be the local Administrators group (BUILTIN\Administrators) on the Connection Server computer or a domain user or group account.Add the account under local administrator and check if that resolves your problem.
BUILTIN\Administrators can't login
Use group policy "restricted group" to push administrators backup into the serverWith Great Regards,
vExpert 2012-2017 | VCP3-5 | VCAP5-DCD | VCP-NV | vSAN Specialist | VDI | Germany