If you find your self with a bunch of old testing machines that appear in your vmware vsphere list and you want to remove them, here is how.
Press the windows key + R and then in the popup box type regedt32
Navigate to:
HKEY_CURRENT_USER\Software\VMware\VMware Infrastructure Client\Preferences
Open RecentConnections Remove any of the old hosts that you no longer need
Navigate to:
HKEY_CURRENT_USER\Software\VMware\Virtual Infrastructure Client\Preferences\UI\ClientsXml
Remove any of the hosts that no longer exist
Tada! You should no longer see those clients when you re-launch the vsphere client.