For a long time, I’ve just dealt with having a massively long list of old VM servers in my vSphere client but today I finally decided to take a minute to do something about it as it was just getting too ridiculous to navigate to find the servers I wanted to use. A quick scour of the web led me to the following registry key, all you need to do is edit the comma separated list, delete out the entries you no longer want, and be on your merry way.
HKCU\Software\VMware\VMware Infrastructure Client\Preferences\RecentConnections