Removes extra config parameters from a virtual machine

    vm_name
        Virtual machine name

    datacenter
        Datacenter name where the virtual machine is available

    advanced_configs
        List of advanced config values to be removed

    service_instance
        vCenter service instance for connection and configuration

def delete_advanced_configs(vm_name, datacenter, advanced_configs,
                            service_instance=None):
    '''
    Removes extra config parameters from a virtual machine

    vm_name
        Virtual machine name

    datacenter
        Datacenter name where the virtual machine is available

    advanced_configs
        List of advanced config values to be removed

    service_instance
        vCenter service instance for connection and configuration
    '''
    datacenter_ref = salt.utils.vmware.get_datacenter(service_instance,
                                                      datacenter)
    vm_ref = salt.utils.vmware.get_mor_by_property(service_instance,
                                                   vim.VirtualMachine,
                                                   vm_name,
                                                   property_name='name',
                                                   container_ref=datacenter_ref)
    config_spec = vim.vm.ConfigSpec()
    removed_configs = _delete_advanced_config(config_spec, advanced_configs,
                                              vm_ref.config.extraConfig)
    if removed_configs:
        salt.utils.vmware.update_vm(vm_ref, config_spec)
    return {'removed_configs': removed_configs}