How to remove items in explorer's new file menu

1. Open regedit
2. Expand "HKEY_CLASSES_ROOT"
3. Find the file type which you want to remove from "New" menu, e.g. for removing MP3 file type look for .MP3 key.
4. Expand it
5. Delete the "ShellNew" key.

The file type will be removed from the "New" menu instantly. No reboot or reloading Explorer needed.