How to Unassociate the Default Action for a Windows File Type

There are quite a few different types of file registered in Windows by default that can be recognized and an associated action can be performed on each one. A number of applications have already been set up to open these files whether they are music files, images, text files or of course, the more important file types like executables. You double click on the file and depending what has it been configured to do will decide what happens next. As more and more software gets installed, more file types are created to handle the extra file formats the new applications require.

To associate a certain type of file with a program is pretty easy and Windows is able to do it for you without a problem, simply right click on the file and select ‘Open with‘, and then ‘Choose default Program..‘. Something Windows is not quite as comfortable at doing is reversing the procedure and removing an association from a file type completely. Although you would more often than not want to change the file’s association from one default program to another because it doesn’t open using the software you expect, there are times when what’s needed is to remove the default action for that type of file altogether. Although Vista and Windows 7 have the ‘Default Programs’ option in the Start Menu or Control Panel to create or change the file associations, you can’t use the same interface to unassociate a file extension, so when you double click a file it won’t be opened by any program. It is possible to dig around in the registry to do it, but unsurprisingly a number of users are not entirely comfortable or experienced enough to use this method. One quick and painless way of changing a file association so it does nothing by default, is by using a little utility called Unassoc which lets you delete the file’s association, or delete the file type completely. Unassoc is freeware and a tiny standalone executable of under 100K. Administrator rights are required for it to function properly so right click and ‘Run as Administrator‘ to start the program.

unassociate file type

Usage is really easy, select the file type from the list and then click ‘Remove file type association (User)‘. The next time you double click that type of file you should only get the ‘Open with‘ dialog because there is now no action associated with it. Be careful with the ‘Delete file type‘ button as the file type will be completely wiped off the system so there will be no association and no information about the type. The ‘Unknown File type‘ window with ‘search the web for….’ will popup if you then try to open a file with that extension. A greyed out remove button means the tool cannot detect an association within the file type.

Compatible with Windows Vista and 7 only.

Download Unassoc

The Unassoc tool is quite handy and does what it’s supposed to in an easy to understand way, but there are a couple of other possible solutions available to get the same result without third party software. These below methods also work perfectly fine in Windows XP as well.

The first method is removing the file association through the command prompt.

1. Open a command prompt with Administrator privileges by right clicking on the CMD icon and ‘Run as Administrator‘.

2. Type ‘assoc .extension=‘, so if you are trying to unassociate a file type with the extension .rcc, use ‘assoc .rcc=‘ etc…

unassociate file type with command prompt

Use the assoc command without arguments to see the list of all current file associations.

The second solution sounds a little odd but works all the same and is the sure fire way to remove the association if those above methods have failed. The idea is to associate the file type with an executable which is then removed from the system and therefore is no longer a valid association. This can be done a few different ways but produces the same result:

1. You can either use a fake executable file by creating a new empty text file or bmp image and renaming it to ‘whateveryoulike.exe‘ (careful not to rename it whateveryoulike.exe.txt). Or you can use an existing executable file which can be deleted from the system or be temporarily renamed. Just make sure a file with the same name is not likely to take its place.

2. Right click on a file of the type you want to unassociate, and click ‘Open with‘ –> ‘Choose default program…‘. Then click the ‘Browse‘ button, locate the executable file created/renamed from step 1 and double click on it. The file should now appear in the ‘Open with‘ window. Click OK. Close any error message windows.

3. Delete the executable file or rename it back to what it was. This will break the association and now if you double click the file, the ‘Open With‘ dialog will display instead of opening an associated program.

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