iPhoto accident with TIF files

Hi folks,

I'm new, and I hope I'm posting this in the right place. I switched from a PC about a year ago and am still learning about my Macbook Pro. In iPhoto this summer, I ticked the box under the Advanced tab in the Preferences for "Save edits [to RAW files] as 16-bit TIF files." This was an experiment that went wrong. About 120 photos were edited before I realized how much space the TIF's were taking up, and that I don't need them at all. How can I undo what I did? I want to delete the TIF files, but not at the expense of losing the original RAW files. Can I get my originals back? What's the best way to do this without messing up the library and confusing iPhoto? I've read that deleting photos from within the Finder window is a huge no-no.

Thanks for reading,

pomology