How to Hide WP Oauth2 Server Admin Menus

function plt_hide_oauth2_server_menus() {
	//Hide the "OAuth2 Server" menu.
	remove_menu_page('codexshaper-oauth-server');
	//Hide the "OAuth2 Server → OAuth2 Server" menu.
	remove_submenu_page('codexshaper-oauth-server', 'codexshaper-oauth-server');
	//Hide the "OAuth2 Server → Clients" menu.
	remove_submenu_page('codexshaper-oauth-server', 'admin.php?page=codexshaper-oauth-server#/clients');
}

add_action('admin_menu', 'plt_hide_oauth2_server_menus', 11);

Where do I put this code?