If you are on the latest version (.8b9), then first you can go into your romlist and press 'tab' in order to open the popup, then select 'show clones' and set it to False (this feature has been present for a while, but didn't actually work correctly until now). Otherwise, you can go into the web front end and manually change all of the info.

To access the web front end, go to a computer on the same network and in a browser, type your pi's ip address. Then click 'database admin' then 'local roms'