Remove kernel version

Sometime you have two or more kernel version, these versions need more disk space . If you want to save disk space, you need remove them.

For ubuntu, I do:

.deb based distro - Debian or Ubuntu Linux

Again find out all installed kernel version:
$ dpkg --list | grep linux-image
Output:

ii  linux-image-2.6.24-19-generic              2.6.24-19.41                      Linux kernel image for version 2.6.24 on x86
ii  linux-image-2.6.24-21-generic              2.6.24-21.43                      Linux kernel image for version 2.6.24 on x86

Now remove linux-image-2.6.24-19-generic with apt-get command itself:

# apt-get remove linux-image-2.6.24-19-generic

OR

$ sudo apt-get remove linux-image-2.6.24-19-generic

More information is in:

http://www.cyberciti.biz/faq/debian-redhat-linux-delete-kernel-command/