press file list button on remote to get recordings up and then press menu button and select settings, the second item 'remove items from trash after' can be set to automatically delete files from the trash after x number of days. Or you can disable the trash altogether by setting the top item 'use trash can in movie list' to no. but empty trash can first.
To delete 'deleted files' manually, from the filelist change to Deleted Items folder (or trash can folder ) and then delete the recordings as you would normally by pressing the red button. That will delete them from the trash can - permentantly deleted