Personally I would not have turned it. Why do that?
If it was shot portrait, edit it portrait in a custom frame size. And export it portrait.
If you must crop it to fit, as you did, your export settings will take care of it.
Tell us your sequence settings and the frame size of your media. I can't actually tell how it was shot, I just assumed that when you said "wrong" you meant portrait instead of landscape.
I would have just made a 1080X1920 sequence and not reduced the size at all.
Why not edit what you shot and play it back on similar devices.
If you shoot portrait, perhaps not the best idea for most footage, but if you do, then play it back portrait.
Just because movie theaters and televisions are landscape, doesn't mean a cell phone has to be.
Oh..you still photographers just never get it!
Well, I admit that might be part of it.
However, I am a big fan of filling the frame with your subject when you can. If you are shooting a few people, landscape is obviously the most likely choice. But if you are using your phone (I will stop saying Smartphone since any phone smart enough to force you to make this decision is probably considered a Smartphone) to shoot a video of a single person, standing by themselves, in front of nothing interesting, why not shoot it portrait? Especially if you are just going to edit it and pass it out to your friends who all have phones that can play it?
I figure that as long as people don't expect to show it in landscape, why edit it that way? It isn't like Premiere Pro won't let you edit portrait images.
Also, portrait shots sometimes make nice PiPs particularly if they were shot for that purpose.