\documentclass[german]{article}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{lmodern}
\usepackage[ngerman]{babel}
\usepackage{csquotes}

\makeatletter
   \renewcommand{\@biblabel}[1]{#1}
\makeatother

\begin{document}

\nocite{*}
\bibliographystyle{example5}
\bibliography{example5}

\end{document}