todo.py

# menu
# choice
# decision
import os #os.system
todos = []  #global variable , external variable

def printMenu():
    os.system('cls')
    print('0-Exit')
    print('1-Print Todo List')
    print('2-Add new Todo')
    print('3-Delete Finished')
    answer = input('Choose (0,1,2,3):  ')
    answer = int(answer)
    return answer

def printTodo():
    print('Todo List')
    print('----------')
    count = 1
    if len(todos)==0:
        print('No more todo')
        return
    for todo in todos:
        print(f'{count}-{todo}')
        count+=1

def deleteFinishedTodo():
    printTodo()
    todel = input('enter item no. to delete: ')
    todel = int(todel) - 1 #index start from zero
    if todel >= len(todos):
        print('index out of Range error')
        os.system('pause')
        return
    todos.pop(todel) #del data at position todel
    print('Selected Item is deleted')

if __name__ == '__main__':
    while True:
        ans = printMenu()
        if ans == 0:
            os.system('cls')
            exit(0)
        elif ans == 1:
            printTodo()
        elif ans == 2:
            newtodo = input('Enter new todo: ')
            todos.append(newtodo)
        elif ans==3:
            deleteFinishedTodo()

        os.system('pause')