如何删除投影仪演示文稿中的黑框？

Question

我想删除出现在每页顶部的黑框，如下图所示。

我想知道我的序言中是否有错误。我该如何修复？这是我的 MWE：

\documentclass{beamer}
\usetheme{default}
\usepackage{helvet}
\usepackage{framed,color}
\definecolor{shadecolor}{rgb}{0.74, 0.83, 0.9}
\useoutertheme[subsection=false]{smoothbars}
\usepackage[frenchb]{babel}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{helvet}
%%%%%%%%%%%%%%%%%paragraphes justifiés%%%%%
\usepackage{ragged2e}
\apptocmd{\frame}{}{\justifying}{} % Allow optional arguments after frame.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\setbeamertemplate{caption}[numbered]
\usepackage[labelsep=period]{caption}
%%%%%%%%%%%%%%%%%%%%%footline%%%%%%%%%%%%
\addtobeamertemplate{footnote}{}{\vspace{2ex}}
\setbeamertemplate{footline}[text line]{%
  \parbox{\linewidth}{\vspace*{-8pt}Title
  \hfill\insertshortsubtitle\hfill\strut\insertframenumber/\inserttotalframenumber}}
  %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\setbeamertemplate{navigation symbols}{}
%%%%%%%%%%%%%%%%%NUMÉROTATION TOC%%%%%%%%
\setbeamertemplate{section in toc}{\hspace*{1em}\inserttocsectionnumber.~\inserttocsection\par}
\setbeamertemplate{subsection in toc}{\hspace*{2em}\inserttocsectionnumber.\inserttocsubsectionnumber.~\inserttocsubsection\par}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%\useinnertheme{circles}
\makeatletter
\patchcmd{\beamer@sectionintoc}{\vskip1.5em}{\vskip0.5em}{}{}
\makeatother
\usepackage{graphicx}
\usepackage{hyperref}
%%%%%%%%%%%%%%%%PLAN%%%%%%%%%%%%%%%%%%%%
\AtBeginSubsection[]
{
\begin{frame}<beamer>
\frametitle{Plan}
\tableofcontents[
  currentsection,
  sectionstyle=show/show,
  subsectionstyle=show/shaded/hide
]
\end{frame}
}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\title[]{Title}
\subtitle[]{Subtitle}
\author[]{Author}
\institute[]{}
\date[] {}
\begin{document}
\frame{\titlepage}

\begin{frame}{Plan}
\tableofcontents    
\end{frame}

\end{document}