Adobe Acrobat is the commercial application for manipulating pdf files. It is expensive at $280 or more dollars, and there are free alternatives. However there are many free programs out there in different stages of usefulness. Perhaps a recommendation from my experience will be helpful.
I suggest you try PDF Split and Merge (PDFsam). There is a basic and an enhanced version. Basic will serve most users fine. Enhanced has a couple more features. Both versions are free software under the GPL. But “free” refers to freedom, not cost. You get the source code and the right to make changes and give them away. But to support development, the PDFsam programmer requires a minimum One Euro donation to gain access to the enhanced version.
I made a donation, and I installed the enhanced version. It adds the ability to encrypt and decrypt pdfs, the ability to set a cover image, and other options that I have not explored. Make a donation if you desire. Let me note, however, that the last version was published in November of 2010. And the basic version will serve most users.
PDFsam is several stand alone features tied together with a console menu. The interface is a bit confusing. I did not see any built in help. The documentation tutorials that are posted online are out of date by a couple of years. When you are not on a deadline, you might want to explore the different tools to see what is there. But my guess is most users will find “Visual document” the most useful.
Visual document will let you pull in multiple pdf files at the same time. You can then drag and drop the pages into the order you desire. You can omit any page, or delete a page you have added and no longer want. Once you are satisfied, choose an output file name, and press the “Run” button.
Here is a video demo I created that shows how to use the Visual document feature. The pdf files I used in the demo were patent files I downloaded from Google’s patent search. I wrote about that in an earlier blog post: