If you added the effect to the track, you can just right click on the effect and delete or modify it in any way. However, if you added the effect to the clip dirrectly then you cannot.
I don't think you're going to like the answer, but if you did an eq edit to the waveform itself, you've probably made a destructive change....
If you used a plug-in, well, you just turn it off, but that doesn't sound like your question.
Just recently, I recorded a stereo acoustic guitar part. The part's a bitch for me to play, but I nailed it on this take. On playback, the part was out of tune with the rest of the song. Less than a quarter tone, but noticeable to me. And in tune to itself. I figured I'd do a pitch change (about 9 cents) on the track, so I cloned it. That way the original was untouched. I archived the original and pitch changed the copy.
Hopefully you're not screwed, but if so, I suggest you do the track clone thing in the future.