Have you the password of smc to stop it?
Step to make it unmanage without the Server access.
Click Start -> Run -> input command “smc -stop”(Password screen display if password attach)
Enter the password to stop it.
Locate to “C:\Program files\Symantec\Symantec Endpoint Protection\”, use Notepad to edit the sylink.xml file, delete the content and save. Then the sylink.xml file will be a empty file.
Delete the sylink.bak and sylinkex.bak file in the same folder
Click Start -> Run -> input command “smc -start”