The recycle bin on your U: drive does not automatically empty when you delete its contents. If you need to create additional space on your U: drive before the daily overnight purging of the recycle bins, you can easily manually delete files from your recycle bin. Just follow the steps in the short video and you should be good to go.
The video has both sound and subtitles, and should play automatically when you click on it.
Manually Emptying the Recycle Bin (mp4)