Add this code in your theme’s functions.php file.

add_action( 'wp_head', 'remove_wpcie_menu' );
function remove_wpcie_menu(){
	remove_filter('wpcfe_after_sidebar_menus', 'wpcie_import_export_sidebar_menu', 10, 1 );
}

Below code removes menu for client’s dashboard only

add_action( 'wp_head', 'remove_wpcie_menu' );
function remove_wpcie_menu(){
	$user_roles = wpcfe_current_user_role();
	if( in_array( 'wpcargo_client', $user_roles ) ){
		remove_filter('wpcfe_after_sidebar_menus', 'wpcie_import_export_sidebar_menu', 10, 1 );
	}
}