Hello Hanako,
there are multiple ways to do this:
1. Tell your client to go to File-PageSetup and empty the footer
2. if talking of IE 5.5 and above, you can set the footer in the registry 
at HKCU/Software/M$/IE/PageSetup. To edit the registry you can use the 
ActiveX-component WScript.Shell. This component is of course not "safe for 
scripting", so if you want to avoid that the user has to allow this every 
time, you may ask him to add your site to the trusted sites on his 
computer - i guess you can do this yourself using the registry..
3. If talking of a CSS 2.0 conformant browser, I guess you can set 
everything with CSS.

enjoy,
Volker