I rented a movie and actually was able to watch it, but in iTunes it still shows up as a download in progress with an error and when I tap the icon it just says I don't have enough memory to continue the download (for the movie that I already watched and the rental time expired for). It is taking up a bunch of space and I want it gone! Please help. I do not have a computer I can get onto at this time and don't want to lose my 100+songs currently stored on my iPhone.
Somewhat bizarrely it is not possible to delete downloads in the iPhone iTunes.
The only way to delete the download, is to contact Apple (the iTunes section) and they will delete it for you. (you can contact support through the desktop iTunes app, or here)