Regarding my previous posts about tutorial how to view Yahoo Messenger conversation without using any password, below I will write the tips and trick how to disable Yahoo Messenger from archive messages.
1. Click Messages –> Preferences
2. Click Archive and choose the options
You can save all of your message archive, but your message will be cleared after you log out from Yahoo Messenger, or you can choose option that no one of your messages will be saved. Just choose the most suitable for you.
Hope this helps :-).