Steps (Website)
Unfortunately this is not possible to do on website. You can only delete photos to reduce the size of your book.
Steps (iOS and android app)
- Tap Edit (top right corner).
- Tap Rearrange (bottom of the page).
- Tap Resize. Use the slider to set the number of pages in the book — photo sizing adjusts automatically.
- Tap Resize, then tap the checkmark (top right corner) to save.