How to Remove File Association

In Windows XP
1. Click the 'Start' button in the lower left corner of the screen.
2. Click 'My Computer' to open Windows Explorer.
3. Click the menu 'Tools > Folder Options' and select the 'File Types' tab.
4. Scroll down the file type list and find the desired file extension. Click on it to select.
5. Click the 'Delete' button, then 'Yes' to confirm.
In Windows Vista
6. Click the 'Start' button in the lower-left corner of the screen.
7. Type 'cmd' and press 'Enter' to open the command prompt window.
8. Type 'assoc .ext= ' and press 'Enter.' Note, 'ext' stands for the file extension you wish to remove from the association list.