Easy way to uninstall old kernel in centos7

1. View the installed kernel
rpm -qa kernel* with root privileges. For
example, the following is the result of kernel view
kernel-headers-3.10.0-123.9.2.el7.x86_64
kernel-3.10.0-123.9.2.el7. x86_64
kernel-tools-3.10.0-123.9.2.el7.x86_64
kernel-tools-libs-3.10.0-123.9.2.el7.x86_64
kernel-devel-3.10.0-123.9.2.el7.x86_64
kernel- 3.10.0-123.el7.x86_64
kernel-devel-3.10.0-123.el7.x86_64
2. Uninstall redundant kernel files kernel-3.10.0-123.el7.x86_64 and kernel-devel-3.10.0-123
The warning message in the process of uninstalling .el7.x86_64 is normal, you don't need to ignore rpm
-e kernel-3.10.0-123.el7.x86_64
rpm -e kernel-devel-3.10.0-123.el7.x86_64
uninstallation is complete , check the kernel list again
rpm -qa kernel*
At this time, the kernel list only has the following results
kernel-headers-3.10.0-123.9.2.el7.x86_64
kernel-3.10.0-123.9.2.el7.x86_64
kernel-tools-3.10.0-123.9.2.el7.x86_64
kernel-tools-libs-3.10.0-123.9.2.el7.x86_64
kernel-devel-3.10 .0-123.9.2.el7.x86_64
now reboot to
reboot