main.dart

class Event {
  int idColumn;
  int idSchedule;
  Event(this.idColumn, this.idSchedule);
  String toString() => 'Col $idColumn - Sched $idSchedule';
}

class Exclusion {
  String date;
  int idSchedule;
  Exclusion(this.date, this.idSchedule);
}

void main() {
  final _events = <DateTime, List<dynamic>>{
    DateTime.parse("2010-10-10"): [Event(1, 2), Event(3, 4)],
    DateTime.parse("2011-10-10"): [Event(5, 6), Event(7, 8)],
    DateTime.parse("2012-10-10"): [Event(9, 10), Event(11, 12)],
  };
  
  final _listExclusions = [
    Exclusion("2011-10-10", 7),
  ];
  
  _listExclusions.asMap().forEach((i, _) {
    if (_events[DateTime.parse(_listExclusions[i].date)] != null) {
      print(_events[DateTime.parse(_listExclusions[i].date)]);
    
      _events[DateTime.parse(_listExclusions[i].date)].removeWhere(
        (item) => item.idColumn == _listExclusions[i].idSchedule
      );
    }  
  });
  
  print(_events);
}