How to reset the icon associated to a given file type?

Question

An application I used (MacCaml) changed the icon of all files with .ml or .oml extension. I would want them to recover their original icon (a blank document). Here is what I have tried (with each time : Finder relaunching, rebooting, creating a new .ml file and opening it with different applications to see if its icon would change) :

• Setting “Always open with another application” (such as TextEdit).
• Going into the application bundle, removing the corresponding .icns file which gives the unwanted icon to all .ml files, replacing it by another .icns file.
• Deleting the application.
• Resetting Finder preferences.
• Trying to change the icon of one of these files (the usual way using Information window).
• Deleting all .DS_Store files.

Nothing worked. Have you got any suggestion ? I think a possible solution would be also to know the answer to the following question :

How to find where the icon associated to a given file is stored ?

For I removed that unwanted .icns file from my computer, though there visibly exists one remaining copy of it which is being used by the Operating System. But using find and fdupes I wasn't able to find any duplicate of that file…

Answer 1

I eventually solved the problem by rebuilding OS X’s LaunchServices database. A way to achieve this is the following command :

/System/Library/Frameworks/CoreServices.framework/Frameworks/LaunchServices.framework/Support/lsregister -kill -r -domain local -domain system -domain user

(It is also possible to use OnyX utility.) A reboot has been necessary.

Answer 2

[Update] RCDefaultApp stopped wotking after Mojave & now seems to have disappeared entirely. There's a similar structure, SwiftDefaultApps which attempts to replace it.

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I have never actually tried this to remove an association, only ever add or change one, but the single go-to utility for Mac file associations has always been RCDefaultApp (freeware).
First released in 2004 & hasn't been updated since 2009... but still works on Mojave.

It installs as a control panel.

1. Select the extensions tab [it may take some time to load up]
2. Scroll to your desired extension.
3. Change the Default App - this includes Default, Disable or Other...[which gives a file picker] as well as any app that has declared it can handle that file type.

I'm guessing Disable may remove all associations & revert the icon - it may need a reboot, or potentially a file.

Extension picked at random, I don't have the ones your question refers to.