Uninstall MarketPress

Help! I installed MarketPress on WP3.0, but now I can;t figure out how to unistall.

There is no listing for it in my plugins section, so I can't just deactivate or uninstall.

I've put it in the mu-plugins folder. I also have Buddy Press installed.

Hope that helps to give you an idea of whats the best thing for me to do. I tried just renaming the marketpressfolder and marketpress.php, but that just threw up some errors.

Am I Ok to just delete the files?

I'd like to reinstall Marketpress when its ready, but just need to put in something simple thats going to work right now, as the site ownser is getting narky about the delay (booooo!).

Thanks.