Delete gridfs file mongo db shell script

if we want to delete gridfs file from mongo db with chunks and file then use below script:

mydoc: is my collection that contain the reference of gridFsFileId for each document

as i want to delete all document below or equal from a particular date:


db.mydoc.find({ "creationTime": { $lte: NumberLong(1485172670719)}}).forEach(
function(mydoc){
  if(mydoc!==null){
    //remove chunk in loop
      db.fs.chunks.remove({
    "files_id": ObjectId(mydoc.gridFsFileId)
    });
    //remove file
        db.fs.files.remove({
           "_id": ObjectId(mydoc.gridFsFileId)
        });
      
      
        //remove from mydoc
      
        db.mydoc.remove({
                "gridFsFileId":  mydoc.gridFsFileId
        });
  }
}
);