i sold one of my cars, to return a plates do i need to do an appointment???

There is a plate return box in the lobby. I'm not sure if they would let u in just for that, if not u can probably leave it with the agents that work at the door.

No, you can walk in for that or just cancel the registration online. https://dmvnv.com/platesurrender.htm You should also complete the Vehicle Resale Notification.

probably, if you want a credit for the remainder of your registration. you would probably sign something about the surrender. I'd recommend it. I sold a car and the new owner never put the title in his name. since I properly surrendered the plates, I did not have to pay the hundreds of dollars in parking tickets.