如何在tkinter中销毁一个类在另一个类上的标签？

import tkinter as tk

class ClassA:
    def __init__(self, root):
        self.root = root
        self.label = tk.Label(root, text="Hello World")
        self.label.pack()

root = tk.Tk()
a = ClassA(root)

class ClassB:
    def __init__(self, a_instance):
        self.a_instance = a_instance

    def destroy_label(self):
        self.a_instance.label.destroy()

b = ClassB(a)
b.destroy_label()