How do I stop file types from launching automatically Is there a way to remove the 'open with' default that is on certain file types? I don't want to replace the the application that opens this file type, I want there to be no application assigned to that type, so that when I download it, no application automatically launches.

Basically is there a way to remove the default application a file type is opened with, and not replace it another application?
That information is stored in the Launch Services database. The lsregister command can be used to manipulate that database. As far as I've been able to gather, you can only unregister an entire application, not an association for a specific file type. You can do that with this command:

/System/Library/Frameworks/CoreServices.framework/Frameworks/LaunchServices.framework/Support/lsregister -u /Applications/&lt;appname&gt;.app


But note that there is an automatic process in OS X that searches the /Applications folder and registers the applications it finds there. So if you have an application that wants to open a certain file type, the association might get recreated even if you have unregistered the application.

Someone may have a better answer than this but hopefully this will be at least a little helpful.