Remove Music

Is there a way to remove certain sounds from a video that was already created?

I do a lot of reediting game trailers, and I want to remove only the song that was uploaded on the video, is that possible?

No.

You can remove sections of audio altogether, not selectively removing a song with other audio going on with the video.

If you only want to remove certain parts of audio, you can right click the clip and select More > Detach audio.