To delete a page:

Choose View > Sidebar.

Choose Thumbnails from the pop-up menu at the bottom of the sidebar.

Select the page to delete.

Choose Edit > Delete.
If you don’t need a page in a PDF file, you can delete it.
Choose View > Sidebar.
Choose Thumbnails from the pop-up menu at the bottom of the sidebar.
Select the page to delete.
Choose Edit > Delete.
When you can delete a page from a PDF document, all the annotations on the page are removed as well.