There are two ways to remove the fog.
1. You read this tutorial:
http://www.worldofminecraft.com/NoFog
2. You just download one of this files and unpack them.
No fog without texture pack:
http://www.file-upload.net/download-398 ... -.rar.html
No fog with texture pack:
http://www.file-upload.net/download-398 ... -.rar.html
(To unpack these files, you will need WinRar | It's the old WoM 2.0.6, but you can also take the newest one with the tutorial)
The originial thread from me with a comparsion below. (Here)