What are you using it for? What did you record it with? If you plan on uploading to YT for example, then you should be able to crop the video with YT tools. If the quality doesn't matter, then you can then redownload the cropped video from YT.
Which editing programs and video players do you have? I recommend googling "how to crop video with (insert program/player name)". If the program(s)/player(s) you have don't work, then I'm sure you could find free versions. I googled 'how to crop video' with multiple results. VLC is free and capable of cropping videos.