only way to uninstall is to flash the kernel u had before cant really uninstall it. you flash a kernel the same way as a rom just without the wipe
Actually, ROM Manager already has a few Kernels on there. So you can simply grab it from ROM Manager, back up your system when it asks, and then let it install. The only effort you really put in is to hit yes a few times.
Edit: Sorry, that's not to say the quoted post was wrong. I just don't think that ROMs are on the app yet, and I know Kernels are. The process is exactly the same though, just for different data.