Forcing Node Offline without F5 Access

You could attach an http monitor that has a recv string that won't match if the service is intentionally being taken down:

ltm monitor http /Common/http_service_is_up { ... recv "Service is up" recv-disable "Service is down" send "GET /status.html\r\n" }

The folks responsible for the node would change the status.html file to read 'Service is down' when they want it removed from the pool.