def exit(self):
    self.frame.destroy()
exit_btn = Button(self.frame, text='Exit', command=self.exit,
    activebackground='grey', activeforeground='#AB78F1', bg='#58F0AB',
    highlightcolor='red', padx='10px', pady='3px')
exit_btn.place(relx=0.45, rely=0.35)
Функция закрытия окна в Tkinter