Can anyone verify if this process to delete the iOS 7 download (but not installed) file works? From Chinese site, WEIPhone (original link:
http://bbs.weiphone.com/read-htm-tid-7022768.html)
"Part 2. Delete iOS 7 firmware downloaded automatically:
Method A: If you have backup in iTunes, recover it. (I didn't test this method, so it's on your own risk.)
Method B: Open Settings->General->Software Update, Click "Install Now". There will be a prompt says "Verifying update...", Wait until this prompt disappear, there will be a spinning wheel on the black background. Immediately press and hold both of the power and home buttons at the same time. DO NOT release the power and home buttons for about 10 seconds. Your device will reboot. It's done. The automatically downloaded firmware will have been deleted."