You can try with that :
void LCDClear(void) {
for (int index = 0 ; index < (LCD_X * LCD_Y) ; index++)
LcdWrite(LCD_D, 0x00);
gotoXY(0, 0); //After we clear the display, return to the home position
}
I just remove the "/8'" part because I don't understand why it's here.
You just have to fill LCD_X*LCD_Y with blank char IMHO.
Let's say if it works