Ok, it works now. Thank you.

Dear @ISDev 

removeFile(id) method requires to pass a file ID as an argument. Not file index, but file ID. You can get the file id in this way:  this.files[file-index].id.

For the test, I have added this.removeFile(this.files[0].id); line to the startUpload() method.

I have added two files and removed one file. The uploader has saved only 1 file in the uploads directory.

Please take a look at my code:

export class AppComponent {
  formData: FormData;
  files: UploadFile[];
  uploadInput: EventEmitter<UploadInput>;
  humanizeBytes: Function;
  dragOver: boolean;

  constructor() {
    this.files = [];
    this.uploadInput = new EventEmitter<UploadInput>();
    this.humanizeBytes = humanizeBytes;
  }

  showFiles() {
    let files = '';
    for (let i = 0; i < this.files.length; i ++) {
      files += this.files[i].name;
      if (!(this.files.length - 1 === i)) {
        files += ',';
      }
    }
    return files;
  }

  startUpload(): void {
    const event: UploadInput = {
      type: 'uploadAll',
      url: 'http://localhost:3001/api/upload',
      method: 'POST',
      data: { foo: 'bar' },
    };
    this.removeFile(this.files[0].id);
    this.files = [];
    this.uploadInput.emit(event);
  }

  cancelUpload(id: string): void {
    this.uploadInput.emit({ type: 'cancel', id: id });
  }

  onUploadOutput(output: UploadOutput | any): void {
    if (output.type === 'allAddedToQueue') {
    } else if (output.type === 'addedToQueue') {
      this.files.push(output.file); // add file to array when added
    } else if (output.type === 'uploading') {
      // update current data in files array for uploading file
      const index = this.files.findIndex(file => file.id === output.file.id);
      this.files[index] = output.file;
    } else if (output.type === 'removed') {
      // remove file from array when removed
      this.files = this.files.filter((file: UploadFile) => file !== output.file);
    } else if (output.type === 'dragOver') {
      this.dragOver = true;
    } else if (output.type === 'dragOut') {
    } else if (output.type === 'drop') {
      this.dragOver = false;
    }
    this.showFiles();
  }

  removeFile(id: string): void {
    this.uploadInput.emit({ type: 'remove', id: id });
  }
}

Best Regards,

Damian