You can use pdftk, it’s a handy tool for manipulating PDF documents.
sudo apt-get --yes install pdftk
pdftk foo-bar.pdf cat 1-12 output foo.pdf
pdftk foo-bar.pdf cat 13-end output bar.pdf
You can use this method to split a PDF in N ways, or to remove pages.
For example, to remove page 13:
pdftk in.pdf cat 1-12 14-end output out.pdf
Or use it to rotate pages and many other things, see man pdftk.
Installation is also possible by downloading a binary (Windows, OS X, Linux) or using Homebrew.