[CentOS] Safe method to remove old kernels

[Lukasz]

Michael Kratz pisze:
> Be very very careful... don't remove the kernel you're running.

after removing actually running kernel, the system will operate 
properly, because kernel and modules are in RAM; so unless you try to 
load a kernel module, or reboot, you are safe

I sometimes make mistakes and remove kernel before installing a new one, 
and it works as good as removing it after installing new