Get to any project, you are allowed to edit your frames
Tap on the duplicate icon (looks like two pieces of paper) in top-right to copy a single frame.
Tap on the add frame icon (looks like a piece of paper with plus) to add new frames.
Tap on the icon with X, you can select "Delete Frame" to delete current frame.
Tap on the icon with X, you can select "Clear Content" to clear current frame.