The ClrHome command clears the home screen — not the I/O screen where the result of commands like Disp or Output is displayed (you'd need ClrIO for that), but the screen where you run programs and evaluate expressions. This isn't usually something you want a program to clear, so this isn't a very exciting command.
It also has the drawback that the ClrHome command itself (or the program it's used in) is displayed on the home screen after it is cleared, so the end result is not a blank screen but something like what you see in the screenshot to the right.
Finally, ClrHome cannot be used inside a function, because functions aren't allowed to modify the state of the calculator.
450 - Invalid in a function or current expression happens when ClrHome is used inside a function.