I SAW THIS RESPONSE BELOW BUT IT DID NOT HELP OR MAYBE I JUST DID IT INCORRECTLY:
What kind of movie or video clip are you trying to mute?
What are you currently using right now to try to remove sound from the movie?
If the video is supported you can use Windows Movie Maker:
In Movie Maker you can import the movie into the timeline.
To make sure your in the Timeline view Click View and select Timeline
Next to the Video you will see Video, Audio/Music
Click the plus sign next to Video to expand
You should now see Video, Transition, Audio
Right click on the Audio Clip and click Volume
Put a Check Mark in Mute Clip and click ok
Proceed to play your movie to make sure you don’t hear sound.
You can then go to Publish To which is under tasks and select where you would like to publish your Movie.
Let me know if this helps you.
