I had my valet key stolen for my Honda Odyssey minivan - do I need to replace all the keys, or can a locksmith / dealer simply reprogram my locks so that the Valet key doesn’t work anymore? Thanks in advance 
as far as I know, the Valet Key will open your car and make it run. I would take it to the dealer where they can reprogram the keys and give you a new set, probably.
Depends. If it is a chipped key the car can be programmed to ignore it and the car won’t start but the door will still unlock with it.
If the key is not chipped you would have to change the locks and Keys.
You have to ask the dealer, keys do different things for different makes and models.
that’s a valet question that you should ask your dealer.
As I remember when we had sedans, the valet key would open the door and start the engine but wouldn’t open the trunk or the glove compartment (if you locked the glove compartment). So what good is a valet key in a minivan, where the rear space is accessible from inside the vehicle?
Still won’t open the glove compartment.
Before you go out on the hassle of changing keys… are you sure the key was stolen? It would really be a pain in the ass to fink the key on your couch after replacing your other keys…