How do I scroll through the LCD vertically with joystick?
The LCD library provides easy functions that activate commands in the LCD itself.  The LCD doesn't have functions that do what you want, so there is no simple vertical scrolling like you're suggesting.

If you need to have it, you'll need to re-write the screen with the content you want to display when the user scrolls around. I can't make any specific suggestions as I don't know the reason you need to scroll around the display this way, but one comprehensive method would be to create a buffer of data the LCD should be displaying, then scroll it using software (move the bytes around the way you want) and then send that buffer to the LCD when it changes.

There may be other more applicable or easier tricks, but that would largely depend on your specific use case and user interface design.