You need to restart the sever after modifying the parameter in carbon.xml
<HideAdminServiceWSDLs>false</HideAdminServiceWSDLs>
After that you should be able to access the wsdl in (I verified with 4.1.1 server)
https://localhost:9443/services/AuthenticationAdmin?wsdl
or
http://localhost:9763/services/AuthenticationAdmin?wsdl