Clean Old Kernels on CentOS

1. Check Installed Kernels

$ rpm -q kernel

2. Clean Old Kernels

## need Install yum-utils ##

## Package-cleanup set count as how many old kernels you want left ##

$ sudo package-cleanup --oldkernels --count=2

3. Make Amount of Installed Kernels Permanent

Edit /etc/yum.conf and set installonly_limit:

 installonly_limit=2