Yes, you can.
Please refer to the following manuals on how to mute video:
▼Mute video (Web Browser)
https://teachme.jp/8/manuals/14366609/
▼Mute video (Mobile App)
https://teachme.jp/8/manuals/14546144/
▼Mute video (Windows Desktop Application)
https://teachme.jp/8/manuals/6678168
*If you delete sound, the sound of the entire video file will be deleted. The original video file with the sound, however, remains intact on your device.
*You cannot delete only part of the sound in the video.