You don't say what kind of computer you're using but since I'm on a Macintosh I'll show you the Mac OS X solution and you'll be surprised how easy it is. In fact, when your question came in I wasn't sure and looked for all sorts of convoluted solutions just to find that it was sitting in front of me the whole time.

The secret on the Mac is to use Preview, which is the default application for viewing PDF (which stands for "portable document format". Did you know that? :-) files on the Mac anyway. Yup, another Apple utility that has secret powers and capabilities.

I picked a PDF that I'd received a while back on the 20 worst drinks you can consume from a health perspective. A handy PDF to experiment with!

Here's what it looks like when I double click on the PDF document to open it in Preview:

The problem is, you can't delete pages from this particular view of the document. You need to switch to an overview. No worries, it's easy. On the right edge click on the double-angle and a menu pops up:

As you can see, under the "View" menu you want to pick the fourth of the four different options, the one that lets you have a page-by-page overview of the document with thumbnails:

For this example, I'm going to delete page two of the PDF, but you'd simply look for and select the blank pages one by one. Once you've selected a page -- which you'll know by it getting an outline and the number being highlighted -- click on the "Edit" menu and marvel at the new options:

Chose "Delete" and... poof! The PDF page is marked for deletion and vanishes from view:

To finish up, simply save the new PDF document and when you examine it, you'll be pleased to see that it's now missing the deleted pages. Quickly and surprisingly easily done.