I recently used up2date to install a new kernel.

Now apt is telling me I have 2 kernels installed and will not allow me to add any other software.

keeps giving errors...

How can I use RPM to uninstall the previous kenrel?

rpm -e kernel-<old version>

Where old version is the old kernel version.

That's an odd error message from apt. It's never a problem to have more than 1 kernel installed at a time (in fact, I have about 5 on the machine I'm typing this on). Is that the exact and complete error message apt gives you? I've never heard of apt having any reason to complain about that. If that's not the exact and complete error message there may be something else wrong with dependencies and it'd be better to fix that before uninstalling an old kernel.