As you might already know, to manage or configure VM's at hardware level 10 which comes with ESXi 5.5 and vSphere 5.5 you will need the vSphere web client (and vCenter) to do so. So what about a standalone or free ESXi 5.5 host ? The easiest way is NOT to upgrade the hardware version to version 10, but to simply keep it at any version below by this way you can fully manage and configure the VM with the C# client (full vSphere client).
I got caught by my enthusiasm to try the new features of vSphere 5.5 and I went and upgraded a VM to version 10 in a lab environment not connected to a vCenter. The quickest way I found to get out of this "unmanaged" situation was to create a new VM with hardware version 9 without disks, after creation I moved the disks of the unmanageable version 10 VM to this new VM and powered it on.
This will give you back control, but you still won't have any of the new features of 5.5.
A other way to manage these version 10 VM's is to install VMware Workstation 10 on you computer and connect to either your vCenter or to your standalone host, by this way you will be able to manage you VM's including the hardware version 10 VM's
More information and screenshot will follow soon in upcoming blog posts