How do you get rid of a Minecraft mod?

Answer 1

First you need to find the .minecraft file.

If you're using Windows 7 or vista, open the start menu on the bottom left and type in "run" on the search field, and you'll open a little window. Here, type in %appdata%/.minecraft

If you're using a Mac, the .minecraft folder is here: [computer username]/Library/Application Support/minecraft

If you're using Linux, the .minecraft folder is here: /home/[computer username]/.minecraft

Here it will be a folder named bin, which you have to delete. The bin folder is basically all updates and everything that has been added after you downloaded the game. When you delete this folder, you'll also delete all the updates, so when you start Minecraft again, you'll have to install all updates again.

Answer 2

It depends - a mod for what exactly?

The how-to depends on the game and the machine you're playing on (PC, PS3, Xbox, etc).

Re-ask the question with the missing information.