ServiceDesk Plus On-Demand now supports request trash feature which is similar to  the recycle bin feature in Windows. Here are a few pointers that will help you understand this new  feature:  

• Trash can be accessed from the requests filter drop- down menu
• All deleted requests will be moved to trash
• The deleted requests will stay in the trash for 30 days after which they will be deleted permanently
• Requests can be recovered/deleted from the trash manually at any given point in time.