Yes, when Kwilt prompts you to do so, this means that your photos & videos are now on the USB storage device connected to your Kwilt device. The Kwilt app always will verify that your files have transferred before asking you if you wish to confirm local deletion from your mobile. In addition, on iPhone and iPad, when you delete photos and videos, you have a certain number of days to restore them from the “Recently Deleted” folder in Apple Photos on your phone if you want them physically back on your phone.