1. Delete pages
Open Delete pages, select the pages to remove and save a new copy.
2. Or keep a few
If you only need a handful, Extract pages saves just those as a new PDF.
3. Check the result
Your original file is unchanged. Open the new copy and check the page count before you send it.
Questions
Is my original file changed?
No. You download a new copy; the original stays as it was.
Related: Combine several PDFs into one file · Split a long PDF into parts · Rotate PDF pages and keep them turned