Remove audio from video file with FFmpeg

You remove audio by using the -an flag.

input_file=example.mkv
output_file=example-nosound.mkv

ffmpeg -i $input_file -c copy -an $output_file

Full ffmpeg documentation here.

You probably don't want to reencode the video (a slow and lossy process), so try:

input_file=example.mkv
output_file=example-nosound.mkv

ffmpeg -i $input_file -vcodec copy -an $output_file

(n.b. some Linux distributions now come with the avconv fork of ffmpeg)

avconv -i [input_file] -vcodec copy -an [output_file]

If you cannot install ffmpeg because of existing of avconv try that .