This will depend on whether the subtitles are hard subs or soft subs.
If they are hard subs then they are burnt/merged into the video, and so cannot be removed.
If they are soft subs then they are overlaid onto the video by the video player and are stored separately from the video, in the container.
If you open up the video in something like VLC say, in the menu bar you go to Video > Subtitles Track, and you can set it to be disabled then the subs are soft and can be removed. If not then they are hard and cannot be removed.
Can also (with the file highlighted in the playlist) go to Window > Media Information. Then in the Codec Details tab you can see what is being used, if there is a stream of type subtitle then it's using soft subs.
If you want to extract the subtitle text so you can view it, then that will depend on the type of file (container) and the format of the soft subtitles.