How to Hide Image Source Control Lite Admin Menus

function plt_hide_image_source_control_isc_menus() {
	//Hide the "Media → Image Sources" menu.
	remove_submenu_page('upload.php', 'isc-sources');
	//Hide the "Settings → Image Sources" menu.
	remove_submenu_page('options-general.php', 'isc-settings');
}

add_action('admin_menu', 'plt_hide_image_source_control_isc_menus', 11);

Where do I put this code?