this isn't exactly what you want but for hiding there is nothing better.
start -> run -> regedit -> navigate to this part HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall
scroll down til you find the one that says world of warcraft and delete it to remove it from add/remove programs make sure to make a copy of it (using export) so as to be able to uninstall it at a later date.
also if your planning on hiding it simply change the shortcut icon to something other then the normal wow one and rename the shortcut to something trustworthy like microsoft data... or somethin
edit: fiddled around and found how to do whatchu ax'd

navigate to HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\World of Warcraft and change the defaultIcon key to something different and the displayName key to something different
