To manage Azure Service Bus with AzureRM.ServiceBus PowerShell cmdlets, you get access using Login-AzureRmAccount, e.g.:
Login-AzureRmAccount
Get-AzureRmServiceBusNamespace -ResourceGroup myRG -NamespaceName myNS
Is there a way get access with AzureRM.ServiceBus using a connection string with manage claims? E.g. as when using .NET Framework NamespaceManager:
$namespaceManager = [Microsoft.ServiceBus.NamespaceManager]::CreateFromConnectionString($connectionString)