To remove Fink, throw get rid of the /sw folder. If you installed XFree86 through Fink also, you'll need throw away /etc/X11, /Applications/XDarwin.app, and /usr/X11R6. Unless you're planning on installing Fink somewhere other than /sw this time, there's not much need to remove that line. You'll get an error every time you open up the Terminal, but it is harmless.
So, I get this error, which I think you were referring to... "/sw/bin/init.csh: No such file or directory." And although it may be harmless, it's somewhat annoying. How does one remove it? Take out a line of text in some text file somewhere?
In the Terminal, type:
That will bring you to a screen that (probably) will have only one line:
"Comment out" this line by putting the # character at the start of it. That makes the system ignore the line. Type control-o to "write out" the change, and then control-x to exit pico.