How do I delete items in a PDF using Adobe Acrobat?

If all you have is the reader, it won’t edit.

No, I have Acrobat.

One of the ideas behind the PDF format is to be able to distribute a document digitally without people being able to edit it.

The only thing i can come up with is to open the page you want to edit in Adobe Illustrator or another vector editing app and then insert the edited page into the original document. If you upload you document i might be able to help you.

You need Acrobat Pro.

You can’t. Acrobat is simply a reader, not an editor. You can download a free pdf editor. Here’s a list: http://en.wikipedia.org/wiki/List_of_PDF_software

You can add and delete or substitute pages in acrobat pro, if the rights haven’t been locked up, but you can’t do much editing on the page. Easiest to recreate the page with your changes and substitute.
You know the difference between the reader and the program, yes? And have the program?
What version is your acrobat?
Do you have a ‘create or edit form’ button on your menu tabs? You could work on a form that way.
Is it a “LifeCycle” form?