How to Hide Reviewkit Admin Menus

function plt_hide_gutensuite_reviewkit_menus() {
	//Hide the "Reviewkit" menu.
	remove_menu_page('gutensuite/reviewkit');
	//Hide the "Reviewkit → Home" menu.
	remove_submenu_page('gutensuite/reviewkit', 'gutensuite/reviewkit');
	//Hide the "Reviewkit → Support Forum" menu.
	remove_submenu_page('gutensuite/reviewkit', 'gutensuite/reviewkit-wp-support-forum');
}

add_action('admin_menu', 'plt_hide_gutensuite_reviewkit_menus', 1000000000);

Where do I put this code?