How can I enable/disable programatically added fields from a custom module? I'm trying to create a custom module for payment. When installed, the module automatically adds two fields to the 'Article' content type.

I have 'enable/disable checkbox' in the form:

Enable: Should mean that people on my live website can use it

Disable: Should mean that no-one can use it (I don't want to remove the variables or the fields in the article content typ, I just want to hide everything in relation with the module)

Is there any hook or any thing that can do that?  Turn the module off?
You should try module_disable(array) function. 
Here is the documentation for it. 
Module Disable Programmatically

You should first check its existence by module_exists and you can also have a look at drupal_uninstall_modules.

I hope this will help you.