When uploading a video to YouTube, you can change the privacy settings for that video to Public, Private, or Unlisted.
Public is the default setting and that means anybody can see your video.
Private means only those you invite to view the video can view it (they must have their own Youtube accounts and the maximum number is 50 usernames). Your video will not come up under any search results or your channel list. If you try to share it with someone who wasn’t invited, they will not be able to connect to it.
Unlisted means your video will not come up in search results or on your channel either. Only those who know the link can view it, and you can share the link with anyone, even those who do not have a YouTube account/username. This means that this video could still be seen by anyone, but only if they guess the link!
If your video is already uploaded, go to your video manager under the drop down menu and you can change the privacy settings for each video as well as DELETE your videos permanently.