You can unpublish a piece of work in a pupil's profile. Click 'Pupils' in the header and select a pupil. Next, choose 'Work' in the tabs at the top of the pupil's profile and select a piece of work using the tick boxes on the left-hand-side. Click the action button, which is the one with three dots ('...') and click 'Unpublish work'.
The work will then have a red cross displayed, meaning it's no longer visible on Pobble, but is still saved in the evidence bank. You can then delete this work if you wish by clicking the action button ('...') again and selecting 'Delete work'.
The work will be removed from Pobble entirely.