I have several servers where old kernels become a problem. Generally either /usr or /boot fills up or runs out of in-nodes. There are a couple of how-tos that give you a command line one-liner that will fix the problem; however, they are all very long and scary. I would rather execute something that I can understand. Thankfully, some kind soul has written a nice simple walk through here. If you are having problems with old kernels piling up, I would suggest taking a look.
If you have to do this on multiple servers, you can simplify the process by just copying and pasting the package name from “dpkg –list | grep linux-image” into one large purge statement. Just remember not to remove your currently running kernel.
sudo apt-get purge linux-image-3.2.0-23-generic linux-image-3.2.0-48-generic linux-image-3.2.0-51-generic