How to suppress page number?

You could use \pagenumbering{gobble} to switch off page numbering.

To switch it on afterwards, use \pagenumbering{arabic} for arabic numbers or alph, Alph,roman, or Roman for lowercase resp. uppercase alphabetic resp. Roman numbering.

For titlepgae

\begin{document}
\begin{titlepage}
\maketitle
\thispagestyle{empty}
\end{titlepage}
\newpage