Actually you don't even need if ($istok

Code:
alias remnicks {
  var %i = 1
  while ($gettok(%LocalNicks,%i,44) != $null) {
    set %GlobalNicks $remtok(%GlobalNicks,$v1,1,44)
    inc %i
  }
}


/set -s %GlobalNicks nick1,nick2,nick3,nick4,nick5,nick6,nick7,nick8,nick9,nick10
/set -s %LocalNicks nick1,nick2,nick4,nick5,nick7
/remnicks
//echo -a %GlobalNicks