如何使用Latex去除pdf顶部的时间

\usepackage{datetime}

\newdateformat{mydateformat}{\THEYEAR}

\pagestyle{fancy}
\fancyhf{}
\rhead{\mydateformat\today}

\documentclass{article}
\usepackage{datetime}
\usepackage{fancyhdr}

\newdateformat{mydateformat}{\THEYEAR}

\pagestyle{fancy}
\fancyhf{}
\rhead{\mydateformat\today}

\begin{document}
This is a sample document.
\end{document}