Exporting phone video to keep the same aspect ratio

I needed to trim a cell phone video for someone and when I brought it into FCPX I got the black bars on either side. When trying to trim or crop the bars don't go away and I don't see anywhere in the inspector when I can have the background be clear.

I've never been asked to do this and was stumped on how to keep the video looking the same.

If you're really trimming the video, it's probably simplest to trim it in the QT player. If you need something more complex make a custom project that matches the video size.

Thank you.