OpenWithView is another cool free application recently released from Nirsoft, OpenWithView lets you enable or disable any program from your open with program list.
OpenWithView will display all the programs stored in your open with program list from which you can disable any program by pressing F8
If you wish to re enable a disabled program, click the program in OpenWithView program list and press F7
After enabling or disabling the selected program click the Save button 
and then close OpenWithView and you will see the changes come into effect.