How can I delete unsaved export files?

I made a video of approximately 40 minutes on my IPad, that I would like to save. When I was exporting this video to my camera roll it failed. When it was almost finished, I got a message that I didn't have enough storage space to save the movie. When I then looked at my storage it showed that iMovie's storing space had grown from 1.1 GB to 5.9 GB. Yet I have no storage room left on my Ipad, and I'm unable to save the movie. Does anyone know how I delete the export file which failed to save on my device?