Simply use: /kickall
It kicks a specified user from all channels were your at, and the user is at.

alias kickall {
  var %n = 1, %b = $comchan($$1,0)
  while (%n <= %b) {
    if ($me isop $comchan($$1,%n)) {
      kick $comchan($$1,%n) $$1 $iif($2-,$2-,Your not welcome here!) 
    }
    inc %n 
  }
}