Solved! Go to Solution.
As per documentation the full command line parameters are
pulselauncher.exe [-version|-help|-stop] [-url <url> -u <user> -p <password> -r <realm>] [-d <DSID> -url <url>] [-cert <client certificate> -url <url> -r <realm>] [-signout|-suspend|-resume -url <url>] [-t <timeout>]
so, yes you should be able to disconnect with command like:
pulselauncher.exe -signout -url <url>
But you found that by yourself, so this is more as of a help to others :-)