Windows - Reset file association to default

At least in Windows 7, once you had set a file association to an file extension, there is no easy way to reset it to default, which is no association and any program.

I had limited luck with assoc and ftype command. It will worked if it works, but, it failed me more of the time. The only reliable way to reset file association to default is to edit the registry with regedit, the steps are (using .c extension for example)

1. Open regedit

2. Find "HKEY_CLASSES_ROOT\.c" and delete it.

3. Find "HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts\.c" and delete it

4. Restart machine or kill and restart explorer if necessary (usually, you do not need to do this)