Windows 10, Windows 8.1, Windows 8, Windows 7, Windows Vista have GUI (graphical user interface) for editing, changing or setting file associations from various file types and protocols to open with a default app. However, it doesn’t provide a tool or utility to unassociate file types and remove file extension associations that already exists in the registry.
Windows OS does have two command line utilities that can be use to remove all file extension associations with its default program or default app. Here’s the guide on how to use the assoc and ftype commands to remove file type association of an extension.
The following tutorial use the example of removing default app that associated .rar file extension to “open with” winrar.exe:
- Open an elevated command prompt with administrator privileges.
- Remove the file extension association from its assigned file type with the following command, follow by ENTER:
Replace .ext with the extension name that needs to be unassociated. For example, to disassociate WinRAR .rar extension, simply type assoc .rar =.
Note that after disassociation of file extension from file type, the default app or default program for the file type no longer been shown in the “Open With” list for the file extension.
- Then, clear and delete the default program used for the Open command when launching files of this type by typing the following command, and press ENTER:
Replace FileType with the actual name for the file type associated to the file extension to be removed from the system. For example, for WinRAR, type ftype WinRAR=.
After disassociation or unassociation of a file extension and file type association, when user double clicks on the particular type of file, the dialog box will be prompted saying “This file does not have a program associated with it for performing this action. Create an association in Set Associations control panel.” and user is forced to click the only OK button. However, it’s possible to right click on the file, and choose Open With… option, then user can select a program from a list of installed programs to open the file, and on the same time, set the correct and proper file association again.