one of my members can access the admin panel? how did he do dat.. i didnt even give him the permission ...

They can't access the admin panel wuth their username and password unless they have admin permissions.
Double check this users permissions (admin panel > permissions (under "user admin") ) User Level should set to User.

Also check their username in the "who is online" box, see if it appears in the admin colours.

yes.. i checked it.. he's name is site admin.. and i was shocked that he changed all my themes.. and all my configuration in forum.. i dunno how he do dat.. maybe there's a bug.. because his name is site admin.. kindly double check please.. ~_~

You need to set their permissions back to user. Also change your password.

Post the link to your forum please?

You also need to make sure his permissions are set to USER not Administrator.
I only see hidden users online, if this persons permissions are set to admin they their username should show up in an orange/yellow colour.

...and as part of his resume, he lists amongst his skills, 'BOT' programmer.

I'd be inclined to keep it 'low-key' at this point.

1. As above, ensure that user does not have the permissions, by checking your Admin Panel.

And if you are not sure it was actually that user, (did you just decide because he's called "SiteAdmin"), then check all your other users.

2. Send a PM requesting that he please choose another User Name, as it is your policy not to allow names that would suggest he is one of your staff.

** Do not accuse the user, or mention, your admin access problems, in your request.

ok tnx alot guys..