When I tried to take Ed-E to the scrap yard I got the message that I couldn't have more than one follower. So I sent Veronica back to the Lucky 38. Now it's still coming up with the same message.
I did the quest for The King about his dog but the dog is nowhere to be seen. I'm assuming the game still thinks he's following me? Or do I have to wait for the time it would take Veronica to reach the Lucky 38?
It is the cyberdog causing the problem - you can have 1 humanoid and 1 robot companion at the same time, so having Veronica would not stop you getting ED-E. Are you on PC or console?
then hit return again and close the console. He should be right in front of you, dismiss him as a companion and he'll either go to the Lucky 38 or his original starting point (the game will tell you where he's going).