You can:
a) just write on top of that location - no need to clear unless you want to
b) clear 4 digits with any of the following
Code:
LCDOUT $FE, $80, REP " " \4    ' perfect the way you have it
or
Code:
LCDOUT $FE, $80, "        "          ' 4 spaces between the quotes
or
Code:
LCDOUT $FE, $80, 32,32,32,32
or
Code:
LCDOUT $FE, $80, $20,$20,$20,$20
or
etc.