Hi Maria C. There are a few steps to delete something from your "Watch Later" list. Once you are on the tab of "Watch Later", click on the video that you wish to remove. Once you are on the video page, you will "Saved" under the left side of the video. Click on that. It will now say "Later", and it will be removed from the "Watch Later" tab. You will want to do these steps for all videos you wish to remove.
To remove a workout from your "I Did This", you will navigate to the "I Did This" tab. On the right of the video that you wish to delete, you will see an "X". Simply click on that and it will be removed from your "I Did This" list. Please note: as soon as you click the "X", the video is removed. There is no warning or question asking if you are sure.
Hope this helps.