You can delete any video uploaded to your YouTube channel. You can't replace a video since any new video upload will get a new URL, but you can modify the existing video.
Delete your own videos
You can remove any videos that you uploaded from your own Google Account. When you delete a video, it's permanently deleted. If you'd like to watch the video in the future, make sure that you have a backup saved.
- Sign in to YouTube Studio.
- From the left menu, select Content
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- Hover over the video that you'd like to delete. Select Options
Delete forever
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- Tick the box to acknowledge that your video will be permanently deleted.
- Select DELETE FOREVER.
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Delete forever 
.When you delete a video from your YouTube channel, we immediately start the video removal process and it will no longer be searchable within YouTube. Data associated with the video, such as watch time, will still be part of aggregate reports, but will not be attributed to the deleted video. You can also delete videos in bulk.
Replace a video
You can't replace a video. Any new video that you upload to YouTube will get a new URL. Instead, you can modify an existing video:
- Trim your video: On a computer, you can cut out the beginning, middle or end of your video.
- Add cards to your video: You can use info cards to add new elements to your video. Cards can show specific websites and more.
- Change your video's title and description:You can organise and change your video's title, category, description and privacy settings.