i forgot my password of picture safe

From what i can tell from other people in the same situation is no you can't retreive those photos.
- Only option i can think of is connecting it to your computer and trying to search the device for the photos.

The usual way of holding down on one of the apps untill they all start to wiggle and select the 'x' on the top left corner of the app to delete it. A warning will apear saying like "Deleting "Photo Safe" will also delete all of its data" - the photos included.