Cannot remove page number when fancy header is used [duplicate]

Question

The page number cant be removed, without removing both header and footer. But i want to keep header and footer and only remove page number

\documentclass[letterpaper, 10 pt, conference]{ieeeconf}  

\IEEEoverridecommandlockouts                              
\overrideIEEEmargins
\usepackage{fancyhdr}
\begin{document}
\maketitle


\fancypagestyle{firstpage}{% Page style for first page
   \renewcommand{\headrulewidth}{0pt}
\renewcommand{\footrulewidth}{0pt}
    \fancyhead[C]{2020 IEEE International Conference on Convergence to Digital World – Quo Vadis (ICCDW 2020)}% Header
  \fancyfoot[L]{978-1-7281-4635-5/20/\$31.00 ©2020 IEEE}% Footer
}

\thispagestyle{firstpage}
\end{document}