In Groove you have the option to view conversations that have been "soft deleted" (as in, not permanently deleted) from your Trash folder. 

The Trash folder is one of the defaults available to all accounts and admins can opt to show or hide this folder using the buttons on the right side of the folder list under Settings > Conversations > Folders

If the Trash folder is hidden, users can still access deleted tickets by searching. Simply type the is:deleted search qualifier into the search bar and you'll be taken to a list of your deleted conversations.