\documentclass{article}
\usepackage{graphicx}
\begin{document}
% crop left
\includegraphics[trim={5cm 0 0 0},clip]{path-to-image}
% crop right
\includegraphics[trim={0 0 5cm 0},clip]{path-to-image}
\end{document}
Use the trim option, which takes four space separated values.
trim={<left> <lower> <right> <upper>}