There are several ways to remove audio from a video using some basic video editing tools for free. Software such as VLC media player, Shotcut, Handbrake and Filmora are some of the free programs available out there in the web.
The beauty about these programs are they are open source and doesn't cost anything to download and use. Unlike other free software which puts a restriction like a water mark on your videos, these above mentioned software actually works and have no restriction to use. You may have to try them out one by one until you find one you like.
To learn more about these free open source video editors, visit : Easytechguides.com
