how do I delete empty pages at the end of my document?

1. Word Processing layout (default)
   1. Select all content on the page to be removed and click delete. Press delete again to remove the page break.
   2. Repeat for each page to be removed.
   3. Do not attempt to remove any pages in this document type via their thumbnail
2. Page Layout
   1. Right-click on the thumbnail representing the page to be removed, and select delete.
   2. Each page is a section and this type of document only supports thumbnail page deletion

See Intro to word-processing and page layout documents in Pages on Mac - Apple Support