To delete a photo/text/sticker, you can long tap the scrap, drag it to the trash can or flick it with your finger. The trash can would show up when you move the scraps. If you want it back, just tap the undo button at the upper-right corner.We also have a "Feedback and Support" section which teaches you how to use different gestures to arrange the pics in a collage. To get to the section, please go to your Profile Settings and tap "Feedback & Support". You can scroll down to view all pages of the tutorial.