Unless and until this feature is added, these SD card sessions can be deleted without formatting the card using Windows Explorer (or the equivalent on a Mac. Whether not formatting will affect the available recording performance or not I can't say.
The directory structure is generated when the Session is created and Record is pressed the first time. The session is not loadable until recording is started for the first time. Took me a while to figure that out. ;-(
The naming of the directories is based on the Artist (A Fine Madness), Performance (Practice 1) and Location (Practice Room)
e.g. I created a sample session with the path to the SD card shown below.
D:\A Fine Madness\Practice 1\Practice Room\Audio
Each directory has only the directory below it except for the Practice Room folder that has the configuration files and the Audio folder for the .wav files.
A Fine Madness-Practice 1-Practice Room.capture
A Fine Madness-Practice 1-Practice Room.cnfg
A Fine Madness-Practice 1-Practice Room.scn
1.audio(0).wav Channel#.audio(n).wav Where n gets incremented if the session is recorded over.
To delete the entire session just delete the whole directory tree. To empty the session delete all of the audio files (.wav)
The presonus support guys helped me figure all of this out.