I have forgotten how to remove these headers.

It really depends on how much clearance you have on your inner fender cuts around the tubes. When my car still had inner fenders, I was able to unbolt the fenderwell headers, and lift them out. I had to twist them while lifting up to allow the contours of the tubes get through the fender holes. My car had pretty generous holes in the inner fenders, however. (I have since removed my inner fenders, and it makes working on the car much easier)