从formBuilder angular 4中删除父字段

import { Component } from '@angular/core';
import { FormBuilder, FormGroup } from '@angular/forms';

@Component({
  selector: 'app-form',
  template: `
    <form [formGroup]="myForm">
      <div formGroupName="parentField">
        <input formControlName="childField1">
        <input formControlName="childField2">
      </div>
    </form>
    <button (click)="deleteParentField()">删除父字段</button>
  `
})
export class FormComponent {
  myForm: FormGroup;

  constructor(private formBuilder: FormBuilder) {
    this.myForm = this.formBuilder.group({
      parentField: this.formBuilder.group({
        childField1: '',
        childField2: ''
      })
    });
  }

  deleteParentField() {
    this.myForm.removeControl('parentField');
  }
}