Thanks to some anonymous employee at VMWare I have a solution. It came from an "Internal Thread" so I don't exactly know who you are...Never the less, get that man a bells.
Here is the code I received:
You need to pass $null to all except the deleteItem parameter. Because the overload of RecomposeVApp that you use has too many parameters, I prefer the overload RecomposeVApp_Task(RecomposeVAppParams recomposeVAppParams). The deleteitem should be an array of Reference which has the Href pointing to the VM to be deleted. Here is a sample script:
Thanks who ever you are