Make a video silent. The audio track is dropped and the video stream is copied into a new file of the same format without being decoded or re-encoded, so the picture is identical to the source and the export takes about as long as reading the file.
Why copy instead of re-encode
Re-encoding decodes every frame and compresses it again, which is slow and loses a little quality each time. Removing audio does not need to touch the picture at all, so it is copied packet for packet.
Before you remove it
The soundtrack is gone from the exported file. If you may need it later, save it separately with extract audio from video first. To replace the sound rather than remove it, the soundtrack tools can process it instead: video volume booster, remove background noise from video, and change pitch of video.