Как вернуться в начало?

Хочу сделать так, чтобы при нажатии кнопки "Отменить" меня возвращало на стартовую страницу выбора файла, но как это сделать вообще? переструктурировать весь код?

import tkinter as tk
import tkinter.filedialog as fd
from tkinter import *
from PIL import Image,ImageTk
from rembg import remove
import os
import sys



window = Tk()

window.geometry('700x500')
window.title("ext")
window.configure(bg='#212121')
window.resizable (width=False, height=False)


def choose_file():
    filetypes = ("Изображение", "*.jpg *.png"),

    global filename 
    global basename

    filename = fd.askopenfilename(title="Открыть файл", initialdir="/",
                                      filetypes=filetypes)
    input_path = (filename)
    basename = os.path.basename(filename)
    fixed_width = 450
    new_res = Image.open(input_path)
    width_percent = (fixed_width / float(new_res.size[0]))
    height_size = int((float(new_res.size[1]) * float(width_percent)))
    sh_res = new_res.resize((fixed_width, height_size))

    global canvas_1

    canvas_1 = Canvas(
    window,
    bg='#212121',
    width = 450, 
    height = 350,
    highlightthickness=0
    )      
    canvas_1.pack()      
    img = ImageTk.PhotoImage(sh_res)      
    canvas_1.create_image(
    0,
    0, 
    anchor=NW, 
    image=img
    ) 
    canvas_1.place(relx=0.20, rely=0.02, anchor=NW) 
    
    global btn_obr

    btn_obr = tk.Button(window,text="Обработать",
                     command=backre_file,
                     width = 20,
                     height = 3,
                     anchor=CENTER,
                     bg='#2F353B',
                     fg='white',
                     borderwidth=0,
                     font='helv39'
                     )
    btn_obr.grid(column=0, row=1)
    btn_obr.place(relx=0.35, rely=0.85, anchor=CENTER)

    global btn_cancel

    btn_cancel = tk.Button(window,text="Отменить",
                     command=(cancel),
                     width = 20,
                     height = 3,
                     anchor=CENTER,
                     bg='#2F353B',
                     fg='white',
                     borderwidth=0,
                     font='helv39'
                     )
    btn_cancel.grid(column=0, row=1)
    btn_cancel.place(relx=0.70, rely=0.85, anchor=CENTER)

    print(btn_cancel)
    
    canvas_1.mainloop() 



def backre_file():
     input = Image.open(filename)
     global removebg 
     removebg = remove(input)
     removebg.save('C:/Users/Nochka/Desktop/Ph/removebg.png', 'PNG')
     fixed_width = 450
     new_res = Image.open('C:/Users/Nochka/Desktop/Ph/removebg.png')
     width_percent = (fixed_width / float(new_res.size[0]))
     height_size = int((float(new_res.size[1]) * float(width_percent)))
     sh_res = new_res.resize((fixed_width, height_size))
     canvas = Canvas(
     window,
     bg='#212121',
     width = 450, 
     height = 350,
     highlightthickness=0
     )      
     canvas.pack()      
     img = ImageTk.PhotoImage(sh_res)      
     canvas.create_image(
     0,
     0, 
     anchor=NW, 
     image=img
     ) 
     canvas.place(relx=0.20, rely=0.02, anchor=NW) 
     

     btn_save = tk.Button(window,text="Сохранить",
                     command=(save_file),
                     width = 20,
                     height = 3,
                     anchor=CENTER,
                     bg='#2F353B',
                     fg='white',
                     borderwidth=0,
                     font='helv39'
                     )
     btn_save.grid(column=0, row=1)
     btn_save.place(relx=0.35, rely=0.85, anchor=CENTER)

     

     canvas.mainloop()


def save_file():
     filetypes = ("Изображение", "*.jpg *.png"),

     global s_file

     s_file = fd.asksaveasfilename(title="Сохранить Файл",defaultextension="png", initialfile="basename", initialdir="/",
                                      filetypes=filetypes)
     print(s_file)
     removebg.save(s_file)



btn_file = tk.Button(window,text="Выбрать файл",
                     command=choose_file,
                     width = 40,
                     height =10,
                     anchor=CENTER)
btn_file.grid(column=0, row=1)
btn_file.place(relx=0.5, rely=0.5, anchor=CENTER)


def cancel():
     btn_obr.destroy()
     btn_cancel.destroy()
     canvas_1.quit()
     print(btn_cancel)
     btn_file.destroy()

     btn_file2 = tk.Button(window,text="Выбрать файл",
                     command=choose_file,
                     width = 40,
                     height =10,
                     anchor=CENTER)
     btn_file2.grid(column=0, row=1)
     btn_file2.place(relx=0.5, rely=0.5, anchor=CENTER)

window.mainloop()