You can use the third-party software "Format Factory" for silence.

Specific steps:

1. First, open Format Factory, enter the Format Factory interface, and select the MP4 video option.

2. Then take the MP4 video format as an example, then click MP4 to enter its editing interface.

3. Click "Add File", enter the "Add File" folder, find the path of the MP4 file you want to edit, and then select this file.

4. Then click "Open", you can see that the video file has been added. Note that there is also an "Output Configuration" option at the top.

5. Click "Output Configuration" to enter the video setting interface. In the audio stream, there is a "Turn off sound" option. Select Yes.

6. Finally, click "OK" to enter the conversion interface. Then click "Start" and the video will start converting. After the conversion is completed, the sound in the video disappears.