old kernels never die?
 

just kidding...

I've updated my Red Hat 9 kernel twice using up2date (which worked without any problems), so now grub gives a choice of 3 versions to boot.

What is the proper way to uninstall one of the old versions (kernel and kernel-source)?

same as any rpm.. "rpm -e packagename" i'd recommend manually editing the grub.conf to avaoid any nasty changes you don't know about.

so is it:

rpm -e kernel-2.4.20-8
and
rpm -e kernel-source-2.4.20-8
and that will remove all the related files?

And then delete the corresponding 4-line entry out of grub/conf?

That's all?

Dont even remove the kernel....Its good to have it around anyways. Just take it out of your grub.conf and it will be as if its not there. If space is an issue, using those commands should do the trick in removing the kernel files. I dont know if it will remove anything you might need, so you may mess something up by doing that.