Feedback on my script

# Ask for an item to add to the list
# Move them to another function which shows the first item with an (1) position
# Add a help menu
# Clearing the screen
# A way to exit the program
# Auto updating list (When ever they add an item append it to the list clear the screen and display the items)

import os
import sys
import time

li_items = []


def clear(): # <--- Clears the screen
    os.system("cls" if os.name == "nt" else "clear")

def intro(): # <--- Introduce the program to the user
    clear()
    print("\nTo-Do List!")
    print("""
    If you feel lost with the commands just
    type ('Help') to see all the commands available
    with information on what they do
    """)
    move = input("Should I proceed? ('Y/n) ").lower()
    if move == 'y':
        main()
    else:
        exit = input("\nWould you want to exit? ('Y/n) ").lower()
        if exit == 'y':
            print("\nGood Byee!")
            time.sleep(1.5)
            sys.exit()
        else:
            clear()
            intro()

def main(): # <--- Where all the work is done!
    clear()
    index = 1
    print("\nAdd your items here!")

    for item in li_items:
        print("\n{}. {}".format(index, item))
        index += 1
    print('\n' + '=' * 20)
    items = input("\n> ")

    if 'Help' in items:
        helper()
        input("Whenever you are done press ('Enter') to continue ")
        main()

    if 'help' in items:
        helper()
        input("Whenever you are done press ('Enter') to continue ")
        main()
    if 'Exit' in items:
        exit = input("\nAre you sure that you want to exit the Script? ('Y/n) ").lower()
        if exit == 'y':
            print("\nGood byee..")
            time.sleep(0.5)
            clear()
            sys.exit()
        else:
            main()

    if 'exit' in items:
        exit = input("\nAre you sure that you want to exit the Script? ('Y/n) ").lower()
        if exit == 'y':
            print("\nGood byee..")
            time.sleep(0.5)
            clear()
            sys.exit()
        else:
            main()

    if 'Rmv' in items:
        delete = input("\nWhich item should I remove? ")
        if delete in li_items:
            li_items.remove(delete)
            clear()
            main()
        if len(delete) == 0:
            input("\nYou forgot to type something.. Press ('Enter') to proceed ")
            main()
        elif delete not in li_items:
            input("\nSorry but this item doesn't exist! Press ('Enter') to proceed ")
            clear()
            main()

    if 'rmv' in items:
        delete = input("\nWhich item should I remove? ")
        if delete in li_items:
            li_items.remove(delete)
            clear()
            main()
        if len(delete) == 0:
            input("\nYou forgot to type something.. Press ('Enter') to proceed ")
            main()
        elif delete not in li_items:
            input("\nSorry but this item doesn't exist! Press ('Enter') to proceed ")
            clear()
            main()

    if 'Done' in items:
        x = li_items
        readyTxt = '\n'.join(str(y) for y in x)
        print("\nCreating your file...!")
        print("\nCreated!")
        file = open('ShoppingList.txt', 'w')
        file.write(readyTxt)
        file.close()
        time.sleep(1)
        clear()
        main()

    if 'done' in items: #(HERE I would like to know how to do something like the bellow)
        x = li_items #(If 'done', 'Done' in items: ) By the way I tried or and it dosn't do what I 
        readyTxt = '\n'.join(str(y) for y in x) # need
        print("\nCreating your file...!")
        print("\nCreated!")
        file = open('To-Do List.txt', 'w')
        file.write(readyTxt)
        file.close()
        time.sleep(1)
        clear()
        main()

    if len(items) > 0:
        li_items.append(items)
        main()
    else:
        print("Please type something!")
        time.sleep(0.5)
        main()

def helper():
    print("""\nAvailable Commands:\n
    -> Help ('Shows all the commands available in the Script')
    -> Done (Creates your file)
    -> Rmv ('Removes the item that you provided')
    -> Exit ('Exits the Script')
    """)

intro()