Where are default apps for file types listed? I would like to batch-remove all associations between XCode and any file type, because it is the default app for so many which I always have to manually set to MacVim.

So I'd like to do this once and for all. Is there some place where these Associations are stored in an editable format? 

To be clear, I am looking for something more powerful than Cmd-I &gt; Open With &gt; Change All which would have to be done manually for each file type for which XCode installs itself as the default app.

I run 10.12.1.
Right click on a file with that file extension, click Get Info (or just select the file and Cmd+I). Now in the Open with section change to an app you want to open that file with, now there should be a button under the place where you set the app to open with that sets all file with this extension to open with that app. After clicking the button, you might need an admin password. Here is a screenshot of the app chooser and the change all button: