When trying to remove a vSwitch in VMware ESXi 5, you may get this error:
Call hostnetworksystem.updatenetworkconfig for object <object name> networksystem on vCenter server <vCenter server name> failed
This error is basically saying that the vSwitch cannot be removed because it’s in use. Under Configuration -> Networking, you should be able to see if any VMs are connected to the vSwitch. Remove the VM from the vSwitch then retry the Remove operation on the vSwitch.