On iPhone, I have 2 rented movies I can't remove: "invalid"

Connect ur iphone to ur pc and delete those movies

Maybe there is something wrong with your iPhone system. If you really can't delete them manually. You could resort to a third-party software program called iTransfer.
Let me show you how to delete them throughly:
1. Run Leawo iTransfer and connect iPad to computer with the USB cable. The software will automatically detect your iPad libraries, and then show the libraries in the left sidebar. Choose "Movies" library and then the contents will be show in the right part of the window. The videos are lying in the window.

2. Hold "Ctrl" key and check the videos you want to delete, then right-click the chosen files and click "Delete" in the drop-down menu. The software will start deleting videos from iPad. The progress bar in the pop-up dialog will show you the percentage of the deleting process. When the deletion is finished, you will get the videos deleted from your iPhone.

When the deleting process is finished, you will find the movies are gone for good in your iPad; and after the backup process, you will get the movies in the target folder.
With Leawo iTransfer, users are able to delete movies on iPad, and back up iPad movies to computer with no efforts. Of course, this software in not only useful for the data transfers of iPad, but also for other iDevices, for example, you can with this software. If you are interested in Leawo iTransfer, you can free download it and have a try.
Part 3. Video Tutorial about Deleting Videos from iPad Permanently Here is the reference: how to remove movies from ipad How to Delete Videos from iPad to Free up Storage Space