How do you remove the default open with application for a file extension? Not change it but remove it so when I try to open it a popup says
"There is no application set to open the document “file.blabla”.
Use RCDefaultApp. With it, you can set the file association to
Another option is to use the command line and
lsregister is located in
/System/Library/Frameworks/CoreServices.framework/Versions/A/Frameworks/LaunchServices.framework/Versions/A/Support/ To see all the available commands, run
/System/Library/Frameworks/CoreServices.framework/Versions/A/Frameworks/LaunchServices.framework/Versions/A/Support/lsregister. See this article for more information.
@Manav proposes in a comment a straightforward and non intrusive way which worked perfectly for me, and I think should be an answer. In a terminal window, run:
/System/Library/Frameworks/CoreServices.framework/Versions/A/Frameworks/LaunchServices.framework/Versions/A/Support/lsregister -u /Applications/Foo.app && killall Finder