How to remove or uninstall old kernals on CentOS

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To list all installed Kernels on system

# rpm -q kernel
kernel-3.10.0-229.4.2.el7.x86_64
kernel-3.10.0-229.el7.x86_64
kernel-3.10.0-229.20.1.el7.x86_64
kernel-3.10.0-229.11.1.el7.x86_64
kernel-3.10.0-327.3.1.el7.x86_64
To remove old or unused kernels on CentOS

First we need to install yum utilities and clear old kernels except recent packages.

# yum install yum-utils

# package-cleanup –oldkernels –count=1

Now the current kernels on system

# rpm -q kernel
kernel-3.10.0-229.4.2.el7.x86_64
kernel-3.10.0-229.el7.x86_64