In that case you could do something like this
$userName = 'domain\user'
$sessMgr = Get-View SessionManager
$sessions = $sessMgr.SessionList |
where{$_.UserName -eq $userName -and $_.UserAgent -match 'PowerCLI' -and $_.Key -ne $sessMgr.CurrentSession.Key} |
Select-Object -ExpandProperty Key
$sessMgr.TerminateSession($sessions)