Old Kernels

rpm -q kernel

yum -y install yum-utils

Keep 0 old kernels

package-cleanup --oldkernels --count=0

Ediy yum for default settings

vi /etc/yum.conf

Current and Previous

installonly_limit=2

Specific Kernel

To remove an unwanted kernel from your operating system:

List installed kernels

rpm -qa | grep kernel

Remove a specific kernel

rpm -e kernel-2.6.18-194.3.1.el5