How to stop a progressbar in Tkinter

I've always been developing in JS a little lost here in Python, if you can help me ...

I wanted to leave the button close without an event until the progress bar is gone, and the progress bar on completion is "indeterminate"

    #Loading page

    root = Tk()
    # Titulo da janela 2

    root.title("Carregando aplicação...")
    janela["bg"] = "white"

    # Tamanho da janela default 2

    root.geometry("230x100+500+500")
    progressbar = ttk.Progressbar(root,orient=HORIZONTAL, length=200, mode='determinate')
    progressbar.place(x=15,y=25)

    progressbar.start(50)

    def fechar():
        root.destroy()


    bt_root_close = Button(root,width=20,text="Fechar", command=fechar)
    bt_root_close.pack(side="bottom")

Thank you!