Estimada Carmine, debes colocarlo en opción borrarlo permanente y te piden que especifiques por opciones, normalmente es porque es envio de trabajo incorrecto y luego te piden colocar la palabra Eliminar y se confirma, asi también hay la segunda opción, es solo borrarlo de la bandeja de entrada que es mas rápido, sin embargo queda guardado en otro sitio

hi Carmine
As Elva has noted, you could request deletion from the database - that will (if you have a VLE integration) go to your TII/VLE manager, who'll approve it (or may ask a couple of questions to check you didn't click that button accidentally, as it's not retrievable). If you're on the New Standard Feedback studio, that's the only option - the remove that Elva mentions isn't there. 

However, as an instructor, you have the choice to save all of the work in an assessment to the main database (that's the standard), not to save it to any database (drawback of that is it won't detect collusion with your your class or between your class & others), or, if it's been enabled locally, just the institution database - which lets you find collusion locally, but not between your students & their friends at a different university