var cursor = db.collection.find()
while (cursor.hasNext()) {
 var doc = cursor.next();
 var docDate = doc.Date;
 var queryDate = "14-03-2015";
 var docDateMillis = new Date(docDate.substring(6,10), docDate.substring(3,5)-1, docDate.substring(0,2)).getTime();
 var queryDateMillis = new Date(queryDate.substring(6,10), queryDate.substring(3,5)-1, queryDate.substring(0,2)).getTime()
 if(docDateMillis < queryDateMillis) {
   db.collection.remove({_id : doc._id})
 }     
}