How to Hide JRM Killboard Admin Menus

function plt_hide_jrm_killboard_menus() {
	//Hide "JRM Killboard".
	remove_menu_page('jrmevekillboard_main');
	//Hide "JRM Killboard → Killboard".
	remove_submenu_page('jrmevekillboard_main', 'jrmevekillboard_main');
	//Hide "JRM Killboard → Configurations".
	remove_submenu_page('jrmevekillboard_main', 'jrmevekillboard_settings');
	//Hide "JRM Killboard → Graphics".
	remove_submenu_page('jrmevekillboard_main', 'jrmevekillboard_graphics');
	//Hide "JRM Killboard → Items".
	remove_submenu_page('jrmevekillboard_main', 'jrmevekillboard_items');
}

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

Where do I put this code?