How To Uninstall Minecraft Mods
Modding Minecraft is a great deal of fun, but if one really gets into the modding experience (and one really should) then there inevitably comes a point at which it is necessary to uninstall old mods and add new ones. Sometimes the uninstall process will be taken care of for you, in the case of a new version of Minecraft being released, at which time all the old program and app data files are overwritten, sweeping away old mods like autumn leaves in a winter storm.
Sometimes however, you'll just want to get rid of a mod because it conflicts with a newer one you want to try, or because you're done with it for the moment. How do you uninstall a mod then, you ask?
Hopefully at some point in the future, when Notch gets around to adding official mod support to the game, there will be an easy uninstall option. At the present time, once you have Minecraft mods that modify any of the existing .class files, removing previously installed mods is something of a pain in the proverbial rear end.
Long story short, the easiest way to uninstall old mods is to simply delete your bin file and any other associated mod files and then run Minecraft. Minecraft will automatically download new files from the server. If that doesn't appeal, then you can always back up your bin files in advance of modding them and save them somewhere, then, when you want to get rid of old mods, you can delete the active bin and replace it with your back up copy.
Either way, the process can be tedious because usually you'll want to just uninstall one mod, not every single mod and not mod managers, like Mod Loader. Unfortunately, in this method, everything is cleared when you replace the bin.
To streamline the re-loading process, I'd advise the keeping of a file with essential mods in it. MC Patcher is one tool that you should always run on a clean .jar because it will enable you to switch between high res texture packs and low res texture packs with the greatest of ease. It's also a good idea to keep a current copy of Mod Loader around the place, because a great many mods make use of Mod Loader these days, and it's simpler to patch Minecraft and reinstall Mod Loader at the same time as you get a clean bin file than to mess around wondering what you have installed and what you don't have installed later.