Scratch disc problems?

Hi,

I recently cut some video on Fincal Cut Express.... now it says I can't open Photoshop elements because there isn't enough disc space on the computer. I see in the preferences in FCE where I changed my scratch disc to my external drive (I guess I shouldhave done this in the first place!). It's good, saying it has 81 gigs. But the problem still remains that I can't open elements. how do i clear the scratch disc so i can open otherapplications up?


Thanks

(i'm new to apple by the way!)