It would be like this:
Code:
on $*:text:/^!point (on/off)/:#:{
  if $nick != YOURNICKHERE { return }
  if $2 == off { 
    set -e %point.off 1 
    msg # Points turn off 
  }
  else { 
    unset %point.off 
    msg # Points turn on 
  }
}

Note: change YOURNICKHERE with yourusername.

!point off to disable point system
!point on to enable.

And replace add.pts alias with this one:
Code:
alias -l add.pts {
  if %point.off { return }
  writeini -n Points.ini $1 Points $calc($readini(Points.ini,$1,Points) + 1)
}