I got the audio CD's loaded on the Ipod just fine. How do I take them off the Ipod now that I've finished the book?

You have to manage the content in iTunes on your computer.  That gives you the option to delete. 

Once you plug in your iPod and it shows up in your iTunes, click on it.  You will have tabs to set up different options however under the main tab there is an option to "manage.." your device.  If you click that then when you see the contents of your iPod you can choose them and then delete them.

I just delete them from Itunes if I won't listen to them again. If I might listen again but don't want them cluttering up my IPOD then I just uncheck them. Then when you sync your IPOD it'll remove them.  You have to have it set up to to only sync checked items. 

On my IPOD touch, I can delete them from the IPOD itself but I think it puts them right back on if I sync it up and don't uncheck or delete them from ITunes.