Safely Remove Unused Kernels In RHEL/CentOS/Fedora

There are three main ways to do it:

1. Use package-cleanup command from yum-utils
2. Use Fedora's dnf remove combined with dnf repoquery
3. Set maximum number of installed kernels in /etc/yum.conf file

First:

# yum install yum-utils
# package-cleanup --oldkernels --count=2

Second:

# dnf remove $(dnf repoquery --installonly --latest-limit 2 -q)

Third:

# vim /etc/yum.conf
installonly_limit=3  #set kernel count

See also:

• https://www.tecmint.com/delete-old-kernels-in-centos-rhel-and-fedora/
• https://www.2daygeek.com/remove-delete-old-unused-kernels-centos-fedora-rhel/