If you reboot into safe mode it should kill all of the IIS and anything else except any startup programs (starup folder/registry run stuff) that you can close manually and that is not at a system level such as the networking components.

There should be two options for safe mode -- safe mode and safe mode with networking support -- choose the first, if you choose with networking it will load all network services which may include some, if not all, of the IIS components.