Thanks for posting your question in the Apple Support Community. I understand that the storage on your daughter's iPhone is full and you're unable to delete photos or videos. Because of this, she's also unable to use any apps.
After deleting photos and videos from the Camera Roll, are you permanently deleting them from the Recently Deleted album? Photos and videos will stay in there for 30 days so that they can be recovered, however if you are sure you don't need them you can delete them permanently with these steps:
Delete photos permanently
If you want to permanently delete your photos or videos within 30 days, you can remove them from the Recently Deleted album. When you delete a photo from this album, you can't get it back.
- Open the Photos app and go to the Albums tab.
- Open the Recently Deleted album and tap Select.
- Tap each photo or video that you want to permanently delete.
- Tap Delete.
Delete photos on your iPhone, iPad, and iPod touch
Once the photos are permanently deleted this should free up some storage space.
If you're still unable to delete photos or videos on the iPhone, you can also plug the iPhone in to a computer and import the photos to the computer. During the import, you'll be given the option to delete the photos off of the iPhone after they've been imported. You can find the steps to import photos below:
Transfer photos and videos from your iPhone, iPad, or iPod touch