How to Hide PlanetStudio Payment Gateway Admin Menus

function plt_hide_planetstudio_payment_gateway_menus() {
	//Hide "PS Gateway".
	remove_menu_page('pspg');
	//Hide "PS Gateway → Orders".
	remove_submenu_page('pspg', 'pspg');
	//Hide "PS Gateway → PayLink".
	remove_submenu_page('pspg', 'pspg-paylink');
	//Hide "PS Gateway → Settings".
	remove_submenu_page('pspg', 'pspg-settings');
	//Hide "PS Gateway → Tools".
	remove_submenu_page('pspg', 'pspg-tools');
	//Hide "PS Gateway → Add-ons".
	remove_submenu_page('pspg', 'pspg-addons');
	//Hide "PS Gateway → Support".
	remove_submenu_page('pspg', 'pspg-support');
}

add_action('admin_menu', 'plt_hide_planetstudio_payment_gateway_menus', 57);

Where do I put this code?