寫了一個tk 程式如下，但遇到兩個問題一直想解不掉，想請前輩們指導

問題1:使用admin_root.destroy()，為什麼關不掉視窗?只能關掉Frame呢?
問題2:為何ID.get()取得的是空值呢?

import tkinter as tk
from tkinter import ttk
from tkinter import Frame
from tkinter import messagebox
import os

#ID內容判斷
def ID_judg():
        aa = ID.get() ############問題2:取得的是空值?
        messagebox.showinfo(aa)
        
#建立介面
def ID_ADD():
    global ID
    id_Root=tk.Tk()
    id_Root.title("建立")
    id_Root.geometry("300x150+380+380")
    id_Root.resizable(width=False, height=False)

    userlable = tk.Label(id_Root,              
                text = "請輸入文字",     
                font = ('微軟正黑體', 12) )
    userlable.grid(row=0, column=0,columnspan=2,pady= 10) 

    ID = tk.StringVar()

    userID = tk.Entry(id_Root, textvariable=ID,width = 15)
    userID.grid(row=1, column=0,columnspan=2,pady= 10)

    BUT1 = tk.Button(id_Root, text = "送出", height = 1, bg = "AliceBlue",width = 10,command=ID_judg)
    BUT1.grid(row=2, column=0,padx= 35,pady= 10)

    BUT2 = tk.Button(id_Root, text = "結束", height = 1, bg = "AliceBlue",width = 10,command=id_Root.destroy)
    BUT2.grid(row=2, column=1,padx= 35,pady= 10)

    id_Root.mainloop()

# 判斷密碼
def netest():
    number = entry.get()
    if number != "123456":
        messagebox.showerror("錯誤", "密碼錯誤")
    else:
        admin_root.destroy()  ############問題1: 為什麼關不掉視窗?只能關掉Frame?
        ID_ADD()


admin_root=tk.Tk()
admin_root.title("login check")
admin_root.geometry("600x270+380+380")
admin_root.resizable(width=False, height=False)

admin_root=ttk.Notebook()
admin_root.place(relx=0.02, rely=0.02, relwidth=0.95, relheight=0.876)


tab1=Frame(admin_root)
tab1.place(x=0,y=30)
admin_root.add(tab1,text='User')

label = tk.Label(tab1,                 
                text = "請輸入密碼",    
                font = ('微軟正黑體', 13) ) 
label.pack(pady=20) 

entry = tk.Entry(tab1, width = 15,show='*') 
entry.pack(pady=7) 

tk.Button(tab1, text = "送出", height = 2, bg = "AliceBlue",width = 10,command=netest).pack(pady=7)


tab2=Frame(admin_root)
tab2.place(x=0,y=30)
admin_root.add(tab2,text='Admin')

label = tk.Label(tab2,                 
                text = "frame2",    
                font = ('微軟正黑體', 13) ) 
label.pack(pady=20) 

admin_root.mainloop()