Selecting a thumbnail in Pages ALWAYS selects the Section containing that thumbnail. Pressing delete deletes what is selected.
Pages creates two types of documents—word processing documents and page layout documents.
In a page layout document, each 'page' is a separate 'section' To add a page you must go to the Insert button or the Insert menu, and choose Page. Note that in the menu attached to the button, all items except Page are greyed. In the Insert menu, many of the items are greyed as well.
In a word processing document, pages are automatically added when text is about to overflow the current page. You can force pages to add a new page by inserting a page break.
To delete a single page in a word processing document, delete the content of that page. The content will disappear, and text below will move up to occupy the now empty page.
OR:
Place the insertion point immediately after the last text on the page you want to delete. Go to the Insert menu and choose Section break. Repeat this process on the page before the one you want to delete.
With the target page now the only occupant of a new section between the two inserted breaks, select that page's thumbnail and press delete.
Optional: Click at the beginning of the page that used to be after the deleted page to put the insertion point immediately before the text on that page. Press delete once to remove the Section break from the previous page.
Regards,
barry