Notes: Cls does not clear sprites, and only clears one layer at a time. If you need to clear both layers, you will need to change the text plane between Cls calls.
SetTextPlane Scroll_A ' This is the default plane
SetTextPlane Scroll_B ' Change to plane b
SetTextPlane Scroll_A ' Back to plane a
Sleep 100 ' Notice only "Hello" was cleared
Cls ' Get rid of "World"