disable recalling user name when signing in

Hi,

I am not sure this is the right place my question.......anyway, I use windows messenger (latest version, I belive) on win xp professional. When I sign in, there are a few my account names (I have multiple accounts) and I can just click my user account an
d type in my password. So with this setting I do not need to type my user account again and again. However, I like to disable this feature so that I need to type my user account (password as well) each time I sign in and I do not want to store my account
names in the computer (so my account name won't appear when I sign in). Could anyone tell me how to disable this (auto recalling feature)? In case, I need to modify registry, I am not an advanced user, so step by step instruction will be appreciated.
Thank you in advance.

anon