I am not quite sure what you mean by “the factory demo” because typically there are a lot of demos loaded in the CVP. If you touch the song part on the right of the start up screen it will open up a menu with all the demos you can scroll under “let’s play”.. If you hit title you will see them all alphabetically. Select one and press play to play it. If you want to play along you can but if you want to silence the midi piano part, press “close” and you will see menu on the bottom right. Touch this then select mixer, then at the top select song. This will open all the midi parts. Usually channel one is the main piano part. Moving the slider to zero will silence this part and then close this screen by hitting the home button on the right side of the display. Touch the song on right and you are ready to play along with it. If you want to see the score and follow it press the Home Screen button again and select score at the bottom.
Hope this helps.
Us older people usually are concerned to touch anything if we are not sure what to do, but modern software is not like that. Play around with these menus, sub menus and screens to learn your way about the keyboard, you can’t do any harm.
Mike