You don't sound like a moron, it's actually something not easy to find out about at a first glance.
There are "pet collectors" scattered around the world in Guild Wars; one is for example next to a Ranger trainer in pre-searing Ascalon. If you have a pet you wish to get rid of, you just speak to the pet trader and he'll take it from you.
I haven't played rangers very much so I can't give you a list of any post-searing traders right now, but I think there's someone just outside a city in an explorable area. Don't recall if it was in Ascalon, Lion's Arch, both, or neither.
