messenger stores this info in the following folder:
/Users/ (your user name) /Library/Preferences/Microsoft
inside these files:
com.microsoft.Messenger.plist
com.microsoft.MessengerDaemon.plist
Microsoft Messenger User Cache.plist
That's where messenger stores info about the logins you've made.
So, to be able of cleaning it anytime you want, just do the following:
1- go to the folder and remove them
2- re-open messenger and go through the initial installation/login steps, making login with the account you want visible
3- close messenger
4- make a copy of these files (just renewed by messenger) in a separate folder (I just call it WHITE and keep it in the same place)
com.microsoft.Messenger.plist
com.microsoft.MessengerDaemon.plist
Microsoft Messenger User Cache.plist
They are now storing the "clean" info.
You can now open again messenger, make login with any other account for other friends, guests, etc...
Whenever you want to get rid of them in the login page, just close messenger, go back again to the folder
/Users/ (your user name) /Library/Preferences/Microsoft
and put back there the copy of them you keept in the "WHITE" folder. that will bring you again to the messenger nice login page with only one user account on the cache next time you open it.
And this is it!
It sucks however that mr. gates did not add a "remove login list" button in the login initial page...