Deleting "Orginal Media"

I am editing a lot of HD footage with Final Cut Pro X right now and I'm running into problems with the Original Media taking up too much space on my computer. I have the original files backed up on 2 external hard drives right now. So my question is, do I need to keep the extra files created in the Original Media folder or can I delete them from my computer? Is there a way to link my files from my external hard drive and not have Final Cut create new ones?

Do you have Copy Files set to on in the import dialogue?

I'm not sure, I've just started out with this version of final cut. How would I change that? And can I delete the copies that were made without affecting my project?

Final Cut Pro menu, Preferences.
Or Command-comma.

The "Imports" tab.

These are the settings used for drag-and-drop importing of media.