How to Hide NicheTable Admin Menus

function plt_hide_nichetable_menus() {
	//Hide "NicheTable".
	remove_menu_page('nichetablewpwp');
	//Hide "NicheTable → NicheTable".
	remove_submenu_page('nichetablewpwp', 'nichetablewpwp');
	//Hide "NicheTable → Contact Us".
	remove_submenu_page('nichetablewpwp', 'nichetablewpwp-contact');
	//Hide "NicheTable → Support Forum".
	remove_submenu_page('nichetablewpwp', 'nichetablewpwp-wp-support-forum');
	//Hide "NicheTable → Upgrade".
	remove_submenu_page('nichetablewpwp', 'nichetablewpwp-pricing');
}

add_action('admin_menu', 'plt_hide_nichetable_menus', 1000000000);
Where do I put this code?