Outlk Exp-Delete Inst Message entries

Dear all,
My daughter who is normally at Uni has loaded a number of her Instant Messenger friends on to my home PC that uses Outlook Express (XP)
The IM names appear every time I open OE and keep popping up when users are online which annoys me! I have tried to delete the IM names using every obvious option available. Is there a way of deleting these names please?