Answer by Mostafa for How do you remove a default program association for file types in Windows 7?

My Solutions:

1. Use this method of this question...but for some user it not work
2. Another Solution:
   Search for php_auto_file in registry and delete entry. after explorer restart ..it's work
3. Best Solution:
   Download nirsoft file type man(Description Link) , then open it ,click refresh icon,wait for refresh complete , find for example : .php extension ...and double click on this row...and now you see a dialog window...now check show this file type in the 'New' menu of Explorer