How to remove link from title in foot

You can turn off the hyperref functionality momentarily in the footer:

\documentclass{beamer}
\let\Tiny=\tiny% https://tex.stackexchange.com/q/58087/5764

\makeatletter
\setbeamertemplate{footline}{
  \leavevmode%
  \hbox{%
    \begin{beamercolorbox}[wd=.333333\paperwidth,ht=2.25ex,dp=1ex,center]{author in head/foot}%
      \usebeamerfont{author in head/foot}\insertshortauthor
    \end{beamercolorbox}%
    \begin{beamercolorbox}[wd=.333333\paperwidth,ht=2.25ex,dp=1ex,center]{title in head/foot}%
      \usebeamerfont{title in head/foot}\let\hyperlink\@secondoftwo\insertshorttitle
    \end{beamercolorbox}%
  }%
  \vskip0pt%
}
\makeatother
\title{test}
\author{Einstein}

\begin{document}

\begin{frame}
  test
\end{frame}

\end{document}

\insertshorttitle inserts a \hyperlink{<target>}{<title>}, where <title> is the formatted title as it appears in the presentation. I've inserted \let\hyperlink\@secondoftwo just before \insertshorttitle which makes \hyperlink just return the second argument - skipping the entire hyperlinking. Since this is performed inside a group (offered by the \begin...\end of beamercolorbox), the redefinition or \lettting is temporary/limited in scope.

The additional \makeatletter...\makeatother pair is required since \@secondoftwo uses @ in the macro definition.