Tools / Remove Pages
Type the pages you want gone — single numbers or ranges like 2,4,6-8.
Separate numbers with commas and use a hyphen for ranges, e.g. 2,4,6-8 removes pages 2, 4, 6, 7 and 8.
The tool blocks removing all pages — at least one page must remain in the output.
Yes, remaining pages are renumbered sequentially in the new file, same as any PDF editor.